Tag Archives: power amplifier

Gryphon Audio Designs Antileon EVO Stereo Power Amplifier

Audio components come and go over the years, but a few designs are so fundamentally correct from their inception that the product’s basic architecture cannot be improved upon. A prime example is the Antileon power amplifier from Gryphon Audio Systems of Denmark. Introduced in 1995, the amplifier is now in a third iteration—the Antileon EVO, reviewed here. Although it features upgraded parts and a few new design tweaks, the Antileon EVO’s fundamental DNA remains the same

That DNA is like a blueprint for creating a no-compromise stereo power amplifier: pure Class A operation, an absolutely unflappable power supply, an overkill output stage, and massive heatsinks. Add completely independent left and right channels (including transformers and power cords), very little negative feedback, balanced circuitry, fully discrete components throughout with no coupling capacitors, and lavish execution with spectacular metalwork and industrial design, and you have the foundation of an amplifier with potentially reference-class performance. All the basic design elements of the original Antileon are here in the EVO, but taken to the next level of execution. 

The Antileon EVO is the very definition of a dreadnought—one look and you know that this amplifier means business. Although rated at 150Wpc into 8 ohms, the Antileon’s size, weight, and construction suggest an amplifier of five times that power output. But as we’ll see, such large hardware is required to ensure that the amplifier delivers its rated power in Class A operation.

Gryphon Audio Antileon EVO Stereo Power Amplifier Rear Panel

Before delving into the Antileon EVO, a little history is in order. Gryphon Audio Systems was founded in 1985 by Flemming Rasmussen, in the same way that many of the best high-end companies started—with the founder building a one-off, no-compromise component for his own use. In Rasmussen’s case, he created a phono preamplifier so that he could better hear exactly how the various phono cartridges he distributed sounded. When a Japanese distributor heard this phono- stage in a CES demo, he immediately asked Rasmussen to build a second unit for him. Unbeknownst to Rasmussen, the distributor loaned the phonostage to Japan’s prestigious Stereo Sound magazine, which promptly awarded the Headamp, as it was called, its highest honor. Gryphon Audio Designs was in business. 

Thirty-six years later, Gryphon is a major manufacturer of a full line of electronics, sources, loudspeakers, and cables. Yet the mindset with which the company was started—building components without commercial constraint—is still alive and well. Although not that renowned in North America, the marque is revered in Europe and Asia. My only previous experience with Gryphon (other than at shows) was an exceptional one. In 2012, I visited Andy Payor of Rockport Technologies to learn more about how he designs and builds speakers (see my review of Rockport’s Altair in Issue 214). In his spectacular custom listening room, Payor played for me his flagship Arakkis loudspeaker, actively tri-amped with all-Gryphon amplification. The sound was transcendent. I wrote a blog about that experience, titled “The Best Stereo System I’ve Ever Heard,” which is exactly what it was at that time. Andy Payor is among a small, very elite group of the world’s top speaker designers who scour the planet for the best-sounding amplification. That he would choose Gryphon to demonstrate his flagship speaks volumes.

The Antileon EVO makes quite a visual statement apart from its sheer muscular bulk. The front panel eschews the typical flat faceplate in favor of polished black-acrylic panels flanking a hemispherical ribbed column. The polished acrylic adds a touch of elegance. A large sub-panel, partially recessed into the acrylic side panels, contains a row of buttons and a display. The left-most button turns the amplifier on and off. Turning the amplifier on automatically launches an elaborate test routine that checks the amplifier’s operating conditions before full power-up. This procedure is accompanied by flashing red indicators in the subpanel. After a few seconds, the test indicators go dark and the amplifier is ready for action. You can also manually run the diagnostic program by pressing a front-panel button. 

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First Watt F8 Stereo Power Amplifier

By my count the F8 represents the sixteenth First Watt power amp authored by the undeniably prolific Nelson Pass. Each unit has been a unique creation said to be “best” in some particular way, though they all happen to look similar because they use the same basic chassis and power transformer. The F8 represents a variation on the popular J2. Its origins go back to 2015, when Nelson had the notion to create a design similar to the J2, based on the SemiSouth Silicon-Carbide R100 power JFET, but using an alternative front-end gain stage. The prototype, says Nelson, was a clear improvement, but because of the J2’s popularity the decision was made to wait. After some additional work over the past six years, that alternative design was finally released as the F8. It is a stereo single-ended Class A amplifier with only two gain-stage devices per channel, a single Toshiba 2SJ74 JFET input, and the SiC R100 power JFET output. Both of these transistors are no longer in production, but available in limited quantities from the First Watt new-old-stock “vault.”      

Circuit-wise, the F8 is quite similar to the J2 amplifier with a virtually identical output stage. However, only one front-end transistor is used instead of six, and it is operated as a current-feedback amplifier as opposed to the J2’s voltage-feedback design. One consequence is reduced gain (only 15dB), but according to Nelson, a simpler front end is more consistent with the single-ended approach to amplifier design and pays off in a purer second-harmonic character, less distortion with lower negative feedback, greater bandwidth, and a higher damping factor. Specifically, comparing the published specs for the J2 and F8, it’s clear that the F8’s damping factor and high-frequency response are twice as good, and that its THD is 0.02% versus the J2’s 0.03%. Unlike the J2, the F8 does not have a balanced input. It also incorporates AC output-coupling in the form of two large electrolytics (10,000µF each) in parallel, bypassed by one polypropylene cap, to eliminate any DC at the output. The resultant bass roll-off frequency is 1Hz. 

Power output is similar, as well. Keep in mind that this is a low-power amplifier, 25Wpc into an 8-ohm load and half that into a 4-ohm load. As such it needs to be carefully matched with a compatible speaker. An 8-ohm speaker with a minimum sensitivity of 90dB would be ideal. The Fleetwood DeVille that I grew quite fond of this past year (and reviewed in Issue 309) was used for all the listening tests. It certainly meets the requirements and offers a sensitivity of 94dB, to boot. The F8’s power dissipation is 170 watts to produce an output of 25Wpc, which means quite a bit of waste heat. Be sure to allow plenty of ventilation around the chassis. Even so, it runs fairly hot to the touch after about an hour of being powered up.

first watt f8 rear

So what does it sound like? Well, it turned out to be the sonic equivalent of Reyka, an Icelandic vodka that has been said to taste dangerously close to fresh water. The F8 started off much like a tabula rasa, a clean slate, distinguished by the absence of inherent sonic colorations. It didn’t sound bright or warm, but consistently took on the flavor of whatever front end I threw at it. That’s not to say that it didn’t have its own sonic imprint. To my way of thinking, what it did right was a logical consequence of a confluence of three factors: simple single-ended circuit topology, wide bandwidth, and an excellent damping factor. 

The resultant airy treble, tonal purity, and superb transient speed were instantly endearing. So was its startling soundstage transparency. It shouldn’t come as a surprise when I tell you that my favorite matching preamp was of the vacuum-tube variety. The F8 allowed tube virtues such as a deep and layered soundstage to shine through, while maintaining an authoritative midbass. Tympani strikes were staggering; drum kits were persuasively resolved with satisfying kick-drum crunch; and brush work was delicate. It was like having your cake and eating it, too. The upper bass and lower midrange weren’t shabby, either. On my favorite performance of the Dvorˇák Cello Concerto in B Minor, with Jacqueline du Pré and the Chicago Symphony Orchestra conducted by Daniel Barenboim [EMI CDC-7476142], the loving collaboration of soloist and orchestra shone with emotional intensity and uncommon clarity. 

When it came to macrodynamics, 99% of the time I didn’t feel that I was missing anything. On a rare occasion, on highly dynamic material, there was a hint of compression. But most of the time the F8 didn’t sound at all like a low-power amp. It managed to project plenty of authority through the power range of the orchestra. Coupled with its robust boogie factor, it was able to extract the music’s dramatic content with total conviction.

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Product Launch: SMSL SA400 High-Resolution Power Amplifier

I think most of us are familiar with SMSL at this stage. While the company started life making affordable devices, they’ve since grown tremendously and have started tackling higher price tiers in turn. The SA400 is their latest device, an amplifier for speakers and 2.1 systems. It offers granular bass adjustment in addition to a whopping 230W per channel (4 ohm) from its dual digital amplifier chips. Premium components promise to minimise noise and interference for clean, dynamic power. The SA400 not only supports RCA and 3.5mm inputs but also XLR balanced and BT5.0.

The SA400 retails for $659.99 USD at the time of writing. You can read all about it and treat yourself to a unit on Apos Audio (affiliate)!

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Original Resource is The Headphone List

Parasound Halo JC 5 Power Amplifier | REVIEW

Though I received the Parasound Halo JC 5 Stereo Power Amplifier, designed by John Curl, along with the Parasound P 6 2.1 Channel Halo Preamplifier and DAC, I felt that each product was different enough that they warranted independent reviews. I’ll get into why I felt that way below, but first let’s dive into this refined beast of a power amp. John Curl has worked as Parasound’s premier designer since 1989. Before that he designed and built a variety of kit for the likes of The Grateful Dead, Jefferson Airplane, Mark Levinson, Wilson Audio, and Mobile Fidelity. Mr. Curl has the audio pedigree to produce something special and the creativity and knowledge to implement an interesting design that I have never seen before in another amplifier. Under the Hood Parasound has an informative in-depth brochure where you can look under the hood of this Halo JC 5 Stereo Power Amplifier. I’ve never seen an amplifier use JFETs, MOSFETs, and bi-polar transistors all in one chassis. Everything about this 400W into 8Ω and 600W into 4Ω with 12W of pure Class A transitioning into Class AB oozes thoughtfulness and attention to detail. Stability into 1.5Ω ensures that the Halo JC 5 [...]

Original Resource is Part-Time Audiophile

PS Audio Stellar M1200 Amplifier

Mention the words “switching” and “amplifier” in tandem and not a few audiophiles are apt to get a queasy look. The knock on Class D amplification is that it tends to sound cold, sterile, amusical. For the most part, there has been something to the opprobrium that has attached to switching amplifiers. So when I saw that PS Audio’s inventive engineer Darren Myers had come up with a switching amplifier called Stellar M1200, I was most curious to hear it. 

The design of the monoblock M1200, which is priced at $5998 per pair, seems calculated to try to overcome the traditional objections to Class D amplifiers. The input section features a venerable 12AU7 tube coupled to a high-current ICE Edge output section. The idea, as near as I can tell, is to try and mate beauty and the beast. And why not? The advantage of Class D amplifiers is that they don’t really produce any significant heat, weigh very little, consume minimal electricity, and deliver a whopping amount of power—in the case of the M1200 no less than 1200 watts into a 4-ohm load, enough to drive just about any extant loudspeaker with ample headroom to hit sonic peaks loud enough to satisfy the most demanding listener.

When I first spotted the M1200, I reckoned that it would be able to drive my Wilson WAMM Master Chronosonic subwoofers easily. I couldn’t help wondering what all that power would be like on the bottom section of my loudspeaker setup. As it happened, however, my system was in flux, with gear whizzing in and out the door; so, I put the M1200s first on the WAMM main loudspeakers without harboring too great expectations. Boy, was I in for a surprise! The M1200 is not a good amplifier; it is a superb one.

There were several enticing attributes of the M1200 that caught my ear, so to speak, from the get-go. The first one was the capacious soundstage that the M1200 produces. It’s always been my experience that the more powerful the amplifier, the larger and deeper the soundstage created by the loudspeaker. Joined to this is a sense of hall ambience, which is very important for a classical buff like me. The M1200 produced all of these in spades. 

On a fine Delos CD of the Brazilian Guitar Quartet playing transcriptions of Bach’s four suites for orchestra, the plusses of the M1200 were easy to detect. For one thing, there was a whoosh of air the instant the quartet began playing the second suite, each guitar firmly and forcefully planted in its own space. One of the attributes of the power that the M1200 offers is a sense of power and drive, not just of the overall performance but of a feeling of dynamic jump for each instrument. To a greater degree than I have heard with most amplifiers, the M1200 truly amplifies the smallest details—the hand of a guitarist inadvertently brushing the strings, a performer sucking his breath in, and so on. The accumulation of these small, almost microscopic, details add up to a more realistic overall sonic landscape. Instruments, whether trumpet, guitar, or violin, emerge as formidable in size and scale.

At the same time, the M1200 is something of a jackrabbit. The amazing damping factor of the amplifier means that it often seems to start and stop a hair faster than many other of its brethren. No matter the musical genre, the feeling of a sense of propulsion is inescapable. In many ways, the music seems to be happening in real time as opposed to that subliminal sense of a split-second time lag. On a Philips LP of Schubert’s sonatas for violin and piano that’s beautifully played by Arthur Grumiaux and Paul Crossley, this alacrity endows the music with a sense of drama. Grumiaux’s bowing has more bite and fervor than most systems would render, as do Crossley’s fortissimos. In my experience, it’s pretty difficult to reproduce a violin’s overtones—the guts of the sound—with any real degree of verisimilitude. The M1200 excels at it. The hall ambience it coaxes into your listening room also means that the lower regions of the piano resound with great fidelity. The piano chords have a 3-D dimensionality to them that is quite winning, particularly in the bass region. Ah, the bass region. I’ll admit it. I’m something of a bass fanatic, and not just because my system is located in the basement. Nor is it that I’m intent on pounding out the low bass on rock recordings, though I’ll confess that I enjoy it upon occasion. No, what I really find illuminating is the degree to which improvements in the bass further the illusion of the real thing throughout the frequency spectrum. In controlling the bass quite authoritatively, the M1200 is able to reproduce effectively the timbral richness of a grand piano, tuba, or guitar. It goes deeper than many competing amplifiers, something that came through vividly on a Pentatone SACD of Bram Beekman playing Bach’s Organ Concerto in D minor. The sustained low organ notes are held with a tautness, even as the melody plays above, that makes for a rewarding listening experience. Ditto for a praeludium by Johann Christoph Kellner; I’ve never heard it better. The linearity of the amplifier means that every note, from bass to treble, exploded out of the loudspeaker with equal force on massive organ block chords. The sound was rich and overwhelming. The depth of hall space was cavernous, as though you were in the cathedral itself feeling the sonic waves emanating from the organ. Forget about the fumbling around that you sometimes hear with other amplifiers that are trying to grasp the very lowest reaches of the organ. The M1200 handles them with aplomb. You’ll hear every note, loud and clear. 

What about the treble region? Here, as you might expect, there are some plusses and minuses. The excellent transparency and power of the M1200 allow it to soar wide open in this fussy sonic region. The grip and control on violin and piano or vocals is most impressive. Take the German counter-tenor Andreas Scholl. On a Harmonia Mundi recording of Bach cantatas, it is impossible to detect a hint of compression with the M1200 when Scholl cuts loose. You can also practically hear the air whooshing through the organ pipes on contemplative treble passages. The automotive equivalent would be flooring it on the Autobahn with no sense of hesitation. The power with the M1200, in other words, is always there, always on tap, always ready to deliver. 

But—you knew there was a “but” coming—the M1200 is simply not on the level of costlier amplifiers in offering an unimpeachable treble region when it comes to tonality. In my view, the M1200 closes the gap between switching and Class A/B amplifiers to a remarkable degree—but not all the way. It has great clarity, but simply remains a little tonally thinner on top than other top-flight amplifiers.

The M1200 poses a real challenge for much of the audio industry. It offers a colossal sound and excellent refinement at what has to be considered a budget price for the high end. PS Audio, which has specialized in power regeneration for many years, is really expanding its ambit. For anyone who has a loudspeaker that is difficult to drive the M1200 is a must-audition. It does so many things so well that it is consistently a joy to listen to in my system. 

Of the amplifiers that I’ve auditioned in this price range, the Stellar M1200 is by far the best, a gangbuster piece of gear that upends many old verities about switching amplification. I could live with it for a very long time. Stellar, indeed.

Specs & Pricing

Frequency response:10Hz–20kHz ±0.5dB, 10Hz–45kHz +0.1dB, -3.0dB
Output power: 600W into 8 ohms, 1200W into 4 ohms.
Signal to noise: > 112dB, [email protected] watts
Gain: 30.5dB
Output impedance: <0.007 ohms, 50Hz, 2.8Vrms
Damping factor: >550 at 50Hz, 2.8Vrms, 4 ohms; >1100, 8 ohms
Inputs: RCA (unbalanced), XLR (balanced)
Outputs: Copper-base nickel-plated binding posts (two pair)
Dimensions: 17″ x 3.75″ x 12″
Weight: 27 lbs. (each)
Price: $5998/pr.

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NAD C658 Streaming DAC and C298 Power Amplifier

NAD’s new C658 streaming DAC packs a huge number of advanced technologies and capabilities into an affordable package. The C658 is a BluOs-enabled streamer that incorporates a DAC with MQA decoding, support for about a dozen music-streaming services, network connectivity, a full suite of preamplifier functions, a moving-magnet phonostage, two subwoofer outputs with configurable crossover, and Dirac Live DSP room correction. You can add inputs now and in the future, thanks to NAD’s Modular Design Construction architecture. The C658 even has a Bluetooth aptX HD receiver/transmitter so that you can listen to music through your wireless headphones. The price? $1649. 

A logical partner for the C658 is NAD’s brand-new, $1999 C298 stereo power amplifier. It, too, is packed with features, including balanced and single-ended inputs, variable gain, line outputs for daisy-chaining multiple amplifiers, a bridging function for monaural operation, an auto-on feature when signal is detected, and remote control. The C298 is one of the first amplifiers to feature a new circuit, called Eigentakt, that is a significant advance in Class D amplification. The Eigentakt output-stage module, created by a new Danish company called Purifi, has extraordinary specifications, including vanishingly low distortion or noise. The design effort was led by Bruno Putzeys, one of the brightest thinkers in switching-amplifier design (Putzeys created the Hypex Ncore Class D module that is the basis for dozens of high-end amplifiers. I describe this new switching-amplifier module, which you are likely to see in many upcoming high-end products, in a sidebar.) 

The C298 is the third NAD amplifier based on the Eigentakt module. The previous iterations are the Masters M33 and M28, each priced at $4999. The C298 is the company’s first attempt to bring the technology to a much lower price point, largely by eschewing the fancy casework of the Masters Series. The C298 is rated at 185Wpc into 8 ohms and 340Wpc into 4 ohms, with a dynamic power rating of 260W into 8 ohms, 490W into 4 ohms, and 570W into 2 ohms. When bridged to operate as a monoblock, the C298 can output a staggering 1000W into 8 ohms.

The C658 network streaming DAC can accept a wide range of inputs (see Specs & Pricing), but will probably be used primarily via its integral support for music-streaming services, and be controlled through the BluOS app. (A full-function remote control is also included with the C658.) BluOS is a wireless digital ecosystem for connecting and controlling a variety of products, including whole-house wireless-audio distribution.        BluOS is a multi-room wireless platform developed by Lenbrook International, and is a sister brand to NAD. BluOS offers a full suite of compatible products for any application. After downloading the app (iOS or Android), you select the BluOS device to stream to, choose music from a streaming service, and enjoy. I logged in to my Tidal and Qobuz accounts, which gave me access to all the music I wanted. You can also connect to any network-attached drives and play music stored on them. Music management is handled through the BluOS app. The C658 shows up as a Roon endpoint (the  C658 was recently Roon certified). BluOS recently made a deal with the Neil Young Archives to provide BluOS users full and free access to the iconic musician’s catalog, all in high resolution. BluOS is compatible with PCM up to 192kHz/24-bit, but lacks DSD support. The optional USB input module will accept DSD up to DSD512, but converts it to PCM at 192/24. The module also accepts USB 2 audio from a computer. Finally, the BluOS app offers a range of free Internet radio services in addition to the paid streaming platforms.

The C658 also allows you to name inputs, set auto-standby time, disable inputs, select between fixed and variable output levels (fixed is the “theater-bypass” mode), trim the gain on each input, engage or bypass the tone (bass and treble) controls, and adjust the display brightness. On the technology side, it’s built around the ESS Sabre 32-bit DAC. The volume control operates in the digital domain, except when the C658 is in the analog-bypass mode.

The C658 is the first NAD Classic Series two-channel product to incorporate Dirac Live. Dirac Live is a DSP room- and speaker-correction system that measures the frequency response and time signature of the sound at the listening position. From this measurement data, Dirac calculates a series of filters that flatten the frequency response and assure correct phase response at the listening seat. Those filters are then downloaded into the C658, which processes the audio signal before the C658’s digital-to-analog conversion stage. In essence, the system “pre-distorts” the audio signal in a way that is the inverse of the distortion created by your speakers and room. That is, Dirac Live modifies the signal driving your loudspeakers so that the final result at your ears is flat in frequency, with most of the sound energy in the room arriving at your ears in phase. Dirac Live doesn’t just look at amplitude information, but also at the room’s time signature. It distinguishes between deleterious reflections, such as floor and ceiling bounce, and later-occurring and lower-amplitude reflections that sound like natural reverberation. 

The version of Dirac Live included with the C658 corrects frequencies up to 500Hz. For the full-frequency-range version, you must pay $99 for the software upgrade. A future software upgrade will provide extensive control over the C658’s subwoofer-output signals. Specifically, it will include a bass-management function as well as clever tricks, such as causing one subwoofer’s output to cancel a standing wave created by the other subwoofer. That feature is like having an active room-resonance-cancelling device built right into the C658 (provided that you have two subs). The C658 hardware, including the two subwoofer outputs, can accommodate this new feature when it becomes available.

Because Dirac Live operates in the digital domain, analog signals at the C658’s input are digitized, processed, and converted back to analog at 192kHz/24-bit. Fortunately, you can bypass the digital conversion on specified analog inputs so that the C658 operates as a pure analog preamplifier. Those bypassed inputs, however, cannot be processed with Dirac Live, and the DSP subwoofer crossover won’t be accessible. (See the sidebar for more about setting up and running Dirac Live.)

Overall, the C658 was fairly easy to operate considering its extensive features and capabilities. I quickly became accustomed to the BluOS app. In typical NAD tradition, the two products’ casework is utilitarian rather than lavish; NAD spends the parts-budget on those components that affect the sound quality. If you prefer a more upscale chassis, NAD offers the Master Series of components.

Listening

I auditioned the C658 and C298 separately in my reference system before using them as a pair. This put each product under the microscope of reference-quality sources, electronics, cables, and the Wilson Chronosonic XVX loudspeakers. For a more real-world situation, I paired the two NAD components with a speaker of commensurate price, the Focal Chora 826, a floorstanding three-way that sells for $2200-per-pair (review upcoming in the April issue). The complete system, without cables, was $5848. I ran balanced interconnects between the two NAD components.

I connected the C658 to my network via an Ethernet cable. NAD also sent to me the Bluesound Pulse 2i, an all-in-one tabletop system ($699) that connects to the BluOS network wirelessly (as I used it) or via an Ethernet port. NAD wanted me to experience how products like the Pulse 2i allow BluOS to function as a whole-house wireless audio system. I wasn’t expecting to receive the Pulse 2i, but discovered that it was a great way to have music outside the listening room. There’s the joke that the audiophile’s way of realizing whole-house audio is to open the listening room door and turn up the volume. I must confess to taking that approach myself. But the ability to place the Pulse 2i in the kitchen, for example, and have full wireless access to high-resolution streaming music controlled by my iPad was compelling.

Starting with the C298, the amplifier had more than enough power to drive the Wilson Chronosonic XVX to any listening level without strain. Even on music with very wide dynamic range (John Williams at the Movies on Reference Recordings) the C298 had plenty of pluck. Peaks were reproduced effortlessly; the bottom end stayed tight and defined at high playback levels; and the soundstage didn’t collapse during the loudest and most complex passages. NAD has long been a proponent of amplification with lots of dynamic headroom, which could be defined as the difference between the amplifier’s continuous power rating on the spec sheet and the clipping point on musical peaks. This approach makes sense; music is dynamic and much of its expressiveness is contained within those dynamic contrasts, and not on steady-state tones. It’s worth noting that the Eigentakt Class D output module is rated at 400W, but NAD specifies the C298’s output power at 185Wpc into 8 ohms. Clearly, there’s a generous amount of headroom.

As with other Class D amplifiers I’ve auditioned, the C298’s bass reproduction was outstanding. This amplifier goes deep, has a nice sense of heft and weight through the midbass, and has terrific dynamic punch on instruments such as kickdrum. An acid-test of bottom-end impact is the track “Octopia” from drummer Simon Philips’ album Protocol II (Qobuz 96/24). In addition to first-rate performances by the entire band (including great guitar work by Andy Timmons), this album showcases Philips’ phenomenal talent, recorded with spectacular drum sound. His huge kit includes many low-tuned toms that put the C298 to the test. The C298 did justice to this album, sounding like an unflappable powerhouse and reproducing the kit with effortless dynamics and impact. 

But it wasn’t just all sledgehammer impact; the C298 also revealed dynamic subtleties and nuance. Throughout the listening, I noticed that the C298 had an unusually satisfying ability to convey music’s rhythmic flow and forward propulsion, from the funky grooves on bassist Brian Bromberg’s Thicker than Water (Tidal MQA) to Ray Brown’s hard-swinging acoustic bass on Soular Energy. This could be the result of the C298’s extremely low output-impedance, which translates to the amplifier having an iron-fisted grip over the loudspeakers’ woofers—either the Wilson’s 12.5″ and 10.5″ drivers or the pair of 6.5″ woofers in the Focal speakers.

The midrange had a nice presence on Norah Jones’ voice on her album Day Breaks (Tidal MQA). Her vocal had good tonality, too, with just a touch of added sibilance. The upper-midrange to lower-treble was a bit forward in perspective, but only a bit. This character brought cymbals and the upper harmonics of instruments to the fore, imparting a lively quality to the sound. Significantly, the C298 lacked the “chalky” haze over the mids and treble that I’ve heard from other switching amplifiers. Instrumental timbre was fairly natural, with excellent resolution of inner textural detail. The C298 was also remarkably adept at revealing subtle instrumental lines. It was easy to hear low-level instruments in the mix or at the back of the hall. The C298’s soundstaging was outstanding—big, open, spacious, and detailed, with precise image placement. If you think of amplifiers in this price as sounding flat, congealed, and a little grainy (compared to reference amplifiers), you’ll be in for a pleasant surprise with the C298.

Dropping the C298 into the middle of a system with $800k worth of source components, electronics, cables, and loudspeakers revealed just what a spectacular bargain this amplifier is. Although not the last word in timbral liquidity, the C298 does just about everything else at a level far above what its price would suggest. It was supremely musical and engaging, particularly the wonderful sense of rhythmic drive and ability to convey dynamic shadings and expression. I have not auditioned many Class D amplifiers, but can confidently say that the C298 is the best switching amplifier I’ve heard.

The C658, in this same system but feeding my reference amplifiers, revealed a good-sounding DAC at this price level. The overall tonal balance was neutral, but with a slight treble emphasis, heard as a bit of additional sibilance on voices. The top end also had a touch of sheen overlying instrumental timbre, and a slight layer of grain. This tended to affect recordings that are inherently bright, rather than blanketing all music. It’s by no means a deal-breaker, but I’ve heard smoother-sounding DACs. 

I was particularly impressed by the C658’s resolution through the midrange; the NAD revealed subtleties of texture and dynamics that are commendable for its price. The bottom end was well defined, and favored articulation over weight, making it easy to follow bass lines. Importantly, the C658 didn’t compress images in the soundstage into two-dimensional representations; rather, image outlines had some tangible space and air around them. The C658 had a good ability to present instruments and voices within a soundstage that was wide and well defined. Dynamics were similarly impressive, with the C658 having the ability to convey subtle nuances of dynamic expression such as gently struck cymbals. 

To get a better feel for the C658’s DAC section performance, I compared it to the AudioQuest DragonFly Red, a $199 overachiever. Although the two products couldn’t be more different in function and capabilities (the DragonFly is a USB stick with no features other than MQA decoding), the AudioQuest, nonetheless, provides a benchmark for what is possible at an entry-level price. The NAD’s bass was a little lighter in weight but more detailed than that of the DragonFly, which was a bit loose and billowy. With the NAD it was easier to follow bass lines, and the overall tonal balance sounded more natural, with the bass better integrated into the rest of the music. The C658 had a much wider and deeper soundstage, with greater spread and separation of instruments in the hall or in the multichannel mix. I also heard greater midrange resolution from the NAD, which better revealed subtle details about how instruments make sounds. The acoustic guitar accompaniment on Norah Jones’ “Come Away With Me” sounded more natural and realistic through the NAD. Overall, the C658 was significantly better sounding than the DragonFly Red. It may not seem fair to compare a $199 USB stick to a $1649 full-featured product; nevertheless, the comparison puts the C658’s DAC performance into perspective. Although you can find better-sounding DACs at the C658’s price, they won’t have the NAD’s extensive capabilities—full preamplifier functions, phonostage, subwoofer outputs with configurable crossover, streaming under BluOS control, and, most significantly, Dirac Live DSP room correction. 

Next, I moved on from the Wilson Chronosonics and listened to the C658 and C298 driving the Focal Chora 826 for some time before engaging Dirac Live room correction. (See the sidebar on setting up and running Dirac Live.) Starting with the stock version that corrects up to 500Hz, I could see in the measured response two peaks of excessive energy in the range from about 80Hz to 180Hz, with two dips below 80Hz. The target curve showed a smoother response after correction, with the gently rising bass of the NAD target curve. In the listening seat, engaging Dirac resulted in more low bass and less midbass bloat. The Focal Chora 826 almost sounded almost like a different speaker in the low end, with greater depth and extension. Kickdrum had more impact, with seemingly much steeper and faster transient attack, coupled with quicker decay. The musical effect was greater punctuation of the rhythm. With the midbass bloat removed, it was much easier to hear nuances in bass playing; pitches were more clearly articulated; and, most significantly, I could more easily hear the starts and stops of each note. With Dirac, individual notes were more distinct in pitch and dynamics. This was true across a wide range of music, from Ray Brown’s acoustic bass on the previously mentioned Soular Energy to Brian Bromberg on Thicker than Water. The overall tonal balance was somewhat lighter and leaner, but this leaning out of the midbass was entirely salubrious; the sound still had plenty of weight and authority, but was cleaner, tighter, and more intelligible.

That impression was with the Dirac version that comes free with the C658, which corrects up to 500Hz. Below this frequency is where room modes are most problematic, and this version of Dirac results in a remarkable transformation of the bass and low bass.

I then switched to the full-frequency-range version, a $99 upgrade, and again measured the system and loaded the new filters from my PC into the C658. I’ve generally believed that it’s best not to try to correct higher frequencies with DSP, for several reasons. First, it’s easy to dramatically change the sound of your speakers (which you presumably like) and get “lost in the woods” trying to find the right tonal balance. It’s easier to do more harm than good. Second, correcting higher frequencies is much more technically challenging that correcting lower frequencies. In my previous experience, it’s best to use DSP to fix the bass and leave the rest of the spectrum alone. 

But that wasn’t the case with Dirac Live. The bass improvements just described were all there, but the effect on the midrange and treble was equally remarkable. Using the NAD target curve (the frequency response the correction system aims for), Dirac didn’t fundamentally change the Focal Chora 826’s smooth and flat tonal balance. Instead, engaging full-range Dirac produced a startling improvements in image specificity, in clarity, in the ability to hear individual instruments through the mix, and in transient response. Sounds started and stopped faster, with less overhang. I also heard a smoother upper-midrange and treble, with less hash. The sound was overall more refined. The impression of individual instruments within a soundstage was heightened.

The full-frequency version of Dirac Live is the most impressive DSP correction system I’ve heard. It is well worth the $99 upgrade. In fact, it made the $2200-per-pair Focal speakers sound like more expensive models.

I next tried Dirac Live with the Wilson Chronosonic XVX, a speaker with much greater bass extension than the Focal. The Wilsons are perfectly positioned in my built-from-scratch listening room, which has good dimensional ratios for evenly distributing room modes. Even with these advantages, rooms will still create peaks and dips in frequency response, caused by the interaction of direct and reflected waves, and between different reflected waves. Two waves combine constructively to produce a peak of energy at certain frequencies, or destructively to create a dip at certain frequencies. Those frequencies are determined by the room’s dimensions. After measuring the system and loading the correction filters for the Wilsons into the C658, I compared with no correction. I did hear an improvement in the bass, but it was an order of magnitude less than with the Focals. The bottom end was a bit more muscular and defined, with slightly better transient performance. 

After lots of swapping individual components in and out of the reference system, and experimenting with Dirac, I finally settled in for some music listening to the system as it was intended; the NAD pair driving the Focal Chora 826 with Dirac properly calibrated. I have to say that the performance of this $5848 system was outstanding, particularly in the bass. The bottom end was quick, articulate, punchy, and had outstanding resolution of pitch and dynamic shading. It was truly a full-range system with a terrific bottom end, a quality that’s very difficult to achieve without spending a lot more money. 

Conclusion

The C658 and C298 can serve as the heart of a capable and powerful music system. The C658 streaming DAC is loaded with all the features needed in today’s digital streaming world, has expandable inputs to accommodate future interfaces, and the BluOS app provides easy and intuitive control over a music library. The C658 can also serve as the heart of a whole-house wireless system. The C298 amplifier is a powerhouse that will drive virtually any loudspeaker. It also has qualities that are consistent with much more expensive amplifiers, including superb soundstaging, clarity of instrumental line, and good resolution of timbre. Bass and dynamics are spectacular, with excellent rendering of pitch and clarity of bass lines. The overall sound is slightly forward in perspective through the midrange and treble, a character that suggests attention to system matching. I can see the C298 delivering terrific performance when paired with much more expensive components. It’s that good.

I would have recommended this pair without Dirac Live, but this DSP speaker- and room-correction system vaults the performance to a new level, without the sonic compromises I’ve heard from some other DSP systems. The improvement in bass extension, clarity, and dynamics is astounding. The full-frequency version of Dirac brings newfound image specificity along with far more lifelike reproduction of transients.

Considered alone or as a duo, the C658 and C298 deliver exceptional performance and value.

Specs & Pricing

C658
Digital inputs: USB, 2x coaxial, 2x TosLink, Gigabit Ethernet RJ45, Wi-Fi 5 (802.11 ac/n), Bluetooth aptX HD (two-way); Apple AirPlay2, HDMI on optional MDC board
Analog inputs: Line in x2 (unbalanced), phono (mm, >80mV overload margin)
Analog outputs: Balanced on XLR jacks, single-ended on RCA jacks, subwoofer output x2
Other input/outputs: IR in/out, 12V trigger in/out, service USB
Formats supported: MP3, AAC, WMA, OGG, WMA-L, ALAC, OPUS, MQA, FLAC, WAV, AIFF; converted DSD supported only via BluOS desktop app
Dimensions: 17 1/8″ x 3 15/16″ x 16″
Weight: 22.3 lbs.
Price: $1649

C298
Output power: 185Wpc into 8 ohms, 340Wpc into 4 ohms
IHF dynamic output power: 260Wpc into 8 ohms, 490Wpc into 4 ohms, 570Wpc into 2 ohms
Mono IHF dynamic power: 1000W into 8 ohms, 1100W into 4 ohms
Inputs: Balanced on XLR jacks, single-ended on RCA jacks
THD: 0.005% at 1W-185W
SN ratio: >98dB (A-weighed, 1W output into 8 ohms)
Input impedance: 56k ohms single-ended or balanced
Dimensions: 17 1/8″ x 4¾” x 15 3/8″
Weight: 24.7 lbs.
Price: $1999

NAD ELECTRONICS
633 Granite Court
Pickering Ontario
L1W 3K1 Canada
nadelectronics.com

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2020 Product of the Year Awards | Solid-State Power Amplifiers

Rogue Audio Dragon 

$3995 

Boasting 300Wpc into 8 ohms (500Wpc in 4 ohms) Dragon is a sophisticated hybrid tube/Class D design that stands atop the Rogue lineup as the most powerful stereo amp it offers today. Indeed, Dragon has enough output to comfortably drive the vast majority of loudspeakers with ease. Perhaps surprisingly, given its tremendous power, it also elicits a near-granular level of finesse and clarity from instruments at the back of the stage. Speed and transient information are naturalistic and lively; tonal balance predominately neutral, with glimmers of midrange warmth and a well-defined presence range. Violin and viola are particularly well rendered and distinct; bass response is superbly controlled. And always lurking at the ready is the voice of authority, eager to reproduce an organ’s pedal point or the left hand of a pianist striking the bottom-octave keys of a concert grand. Not just another high-powered beast, Dragon is truly a splendid and easily attainable amplifier that will proudly grace any system. 

aesthetix_atlas_2

Aesthetix Atlas Eclipse Mono 

$28,000/pr.

The Aesthetix Atlas Eclipse Mono is a powerful amplifier that delivers like few others on the promise of hybrid technology. The tube input stage actually allows the amplifier to capture almost all of the body, texture, and sense of space offered by the best all-glass designs. At the same time, the solid-state output stage provides the bass slam and control seemingly available only with high-power transistor amplification. Designer Jim White has taken his widely admired Atlas amplifier to new heights by carefully matching all of the output transistors, using the latest in custom-designed StealthCap technology, upgrading the power supply, and redesigning the casework to reduce resonances. The audible result of these efforts is seemingly unlimited power (rated 300Wpc into 8 ohms and 600Wpc into 4 ohms) with a pristine transparency that the earlier versions of this amplifier could not quite achieve. With this open-window-to-the-world clarity comes three-dimensional instruments, rich tonal color, expansive soundstage, a blacker background than the original Atlas, and subterranean bass. For those of you using dedicated subwoofers, the Atlas Eclipse offers a separate input followed by a built-in high-pass crossover that allows the user to roll off the low frequencies going to the loudspeaker driven by the Atlas, which in turn allows for a much cleaner transition between main speaker and subwoofer. The Atlas Eclipse Monos are a celebration of hybrid design fully realized—truly deserving to be called Product of the Year.

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McIntosh Announces MHA200 Vacuum Tube Headphone Amplifier

The following is a press release issued by McIntosh.

Binghamton, NY – February 4, 2021 McIntosh, the global leader in prestigious home entertainment and ultimate-quality audio for 70 years, is proud to introduce the MHA200 Vacuum Tube Headphone Amplifier.

The McIntosh MHA200 Vacuum Tube Headphone Amplifier is designed for discerning headphone enthusiasts who demand the most from their headphones. Its versatile set of connectivity options, including balanced inputs and outputs, allows for nearly all headphone types to be connected to enjoy an extraordinary personal listening experience.

A pair of 12AT7 and 12BH7A dual triode vacuum tubes power the compact MHA200. The 12AT7 vacuum tubes amplify the incoming audio signal while the 12BH7A tubes provide the power to drive the output to the headphones with low distortion. The MHA200 uses a pair of McIntosh’s Unity Coupled Circuit output transformers to deliver pristine audio. The Unity Coupled Circuit is the same technology McIntosh was founded on in 1949 and is still used in their vaunted full-size home audio vacuum tube amplifiers such as the timeless MC275 and the more recent MC1502. Indeed, the MHA200 shares many physical design traits with the aforementioned vacuum tube amplifiers.

A wide assortment of connectivity options come on the MHA200. For attaching headphones, there are 3 options: a pair of 3-pin balanced XLR connectors for dedicated Left and Right balanced output; a 4-pin balanced XLR connector for balanced stereo output; and a 1/4″ stereo headphone jack. For connecting the MHA200 to a home music system’s source components, it has 1 set each of both balanced and unbalanced inputs. Thanks to the MHA200’s small size of just 6-1/8″ (15.6cm) wide x 9-1/8″ (23.2cm) deep and its balanced inputs, it can be placed close to the listening position for ease use, with long balanced cables connecting it to the audio system without fear of signal loss.

The MHA200 takes advantage of unique McIntosh technologies to create the best possible personal listening experience. The Unity Coupled Circuit transformers have been adapted to produce 4 headphone impedance ranges of 32 – 100, 100 – 250, 250 – 600, and 600 – 1,000 Ohms at 500mW so that virtually every headphone can receive legendary McIntosh sound quality and performance.

McIntosh custom designed and manufactured the output transformers to match the tube amplifier section to the headphone output section in order to ensure maximum power transfer for various headphone loads. Instead of having to adapt to the impedance of the headphones with voltage gain in the input stage, the Unity Coupled Circuit output transformers’ secondary windings ensure the full power of the MHA200 is available regardless of the impedance of the headphones. A custom, high-performance, and highly efficient toroidal power transformer with low mechanical hum and a low magnetic field, which helps reduce electrical noise, provides clean power to the amplifier.

The user can select the best impedance range for the headphones via the LOAD knob. The VOLUME knob allows the MHA200 to be connected directly to music sources that only have a fixed volume output without needing a preamplifier for volume control. Conversely, if the component has variable volume output, then the VOLUME knob should be set to the center Unity Gain point and the volume controlled by the variable output component.

The MHA200 features a custom formed stainless steel chassis with a polished mirror finish that will accentuate the glow of the vacuum tubes, making it a statement piece to display and to use with pride. A vintage die cast aluminum McIntosh name badge adorns the side. A Power Control input and output allows the MHA200 to turn on and off with other connected McIntosh components, such as preamplifiers, CD players, turntables, or media steamers.

Pricing and Availability

Orders for the MHA200 can now be placed with Authorized McIntosh dealers with shipping expected to begin in March 2021 to the United States and Canada, and to the rest of the world shortly thereafter.

Suggested retail price (VAT, shipping and any customs duties related to current standards of individual countries are excluded): $2,500 USD.

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NAD Launches CI 16-60 DSP Amplifier

The following is a press release issued by NAD Electronics.

Pickering, Ontario, canada January 18, 2021 – NAD Electronics, the highly regarded manufacturer of high-performance audio/video components, announced an all-new advanced amplifier targeted squarely at high performance distributed audio systems. The CI 16-60 DSP ($2,499 U.S. MSRP) delivers 16 x 60 watts per channel with unique features and will be available in mid-February.

The CI 16-60 DSP is a highly versatile, robust amplifier built for the demands of professional installations. Delivering a conservative 60 watts per channel at 8 ohms into all of its 16 channels, each pair of channels is with bridgeable to 140 watts per channel if more power is desired. The hybrid digital amplifier platform delivers stable and efficient power with high current capability all in a 2U rack space. The CI 16-60 DSP uses a customized version of the proven Hypex UcD output stage to deliver great load invariant power with extremely low distortion and noise in the audible range. Every detail of this design has been carefully executed to wring out the best possible performance. Designed to deal with the demands of the custom installation world, the CI 16-60 can effortlessly handle long cable runs and difficult speaker loads.

The CI 16-60 DSP is an IP-controlled amplifier which allows the installer to configure and calibrate via a web-based user interface. The user interface offers access to multi-channel digital signal processing (DSP) providing detailed equalisation control. A virtual patch bay permits any input to be routed to any, or multiple outputs without the need to create physical connections. In addition, the UI offers insight into temperature and power status, as well as basic troubleshooting functions like power cycling, factory resetting and updating. Rounding out the CI 16-60’s impressive feature set are loop through jacks on all the inputs making it easy to daisy chain sources to multiple amplifiers for larger installations.

“NAD’s CI 16-60 DSP amplifier joins the CI 8-120 DSP and CI 8-150 DSP distribution amplifiers highlighting one of the brand’s strongest features which of course is our amplifier platforms, commented Joe de Jesus, Lenbrook’s Product Manager for CI. The brand has a reputation for rock-solid amplification and a tonal balance that seems to shake hands with virtually any speaker it powers. Our clients can expect the same exacting standard. For example, this new CI 16-60 DSP adheres to the same stringent sonic tests as our best traditional amplifiers. Quite simply, that sonic signature and rock-solid reliability is what separates NAD from the rest.”

FEATURES & DETAILS

  • Platform accessed through IP control
  • Custom web app manages DSP calibration, IP control and more
  • 16 Channels x 60 Watts @ 8 ohm
  • Bridgeable – any consecutive channel pair bridgeable to 2 x 140 Watts @ 8 ohm
  • Renowned NAD sonic signature
  • Effectively handles long cable runs and difficult speaker loads
  • Global Input/Output and Individual Channel Input and Output
  • 2U Rack height
  • 5W Standby Mode, 3W
  • Network Standby
  • 12V Trigger In; IR In/Out
  • Multiple Power-up options as well as Eco Mode
  • Universal AC Power Supply

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Audio Research Corporation Reference 160S Stereo Power Amplifier

The Audio Research Corporation needs no introduction. Its foundational contribution to the audio world is well established. I have lusted after various ARC products over the last 35 years. Pretty much all ARC’s tube gear—from the 1987 SP9 preamp a neighbor owned when I was starting out to the more recent REF250 power amps, and many products in between—has fostered a kind of “inner life” within recorded music. The even more recent Reference 160M monoblocks vaulted my interest yet higher. When I heard them at industry shows and in audio shops, they sang with a clarity, finesse, and dynamic command that struck me as a new frontier for ARC. Now, we have the stereo version of the 160M—the $22k Reference 160S.

I didn’t have a pair of Ref160M ($34k) monos on hand for direct comparison, but with the stereo Ref160S in my system I did hear qualities very similar to those of the monos in other systems. This is no surprise, since the Ref160S has the same circuitry, tube complement (four KT150, two 6H30 per channel), and power rating (140Wpc) as the monos. The feature set is also the same—output-tube auto-bias, front-panel output-tube monitoring, ultralinear/triode-mode buttons, and “floating” power meters on a see-through faceplate. On the rear panel we have 4-, 8-, and 16-ohm taps, an output-tube hour-counter, a cooling fan control, an auto shut-off, and RCA/XLR input switches. The Ref160S is a bit larger in all dimensions (mostly depth) and weighs a lot more than a single Ref160M (100 pounds vs. 56 pounds), no doubt to accommodate two channels’ worth of stuff in a single chassis. (The only circuitry difference—as far as I can tell—is that the Ref160S shares one power transformer for both channels, whereas the 160M has, of course, one transformer per amplifier.) The stereo amp actually has a slight edge over the mono in aesthetics in my opinion: The 160S’s transformers are covered in their own nice-looking vented cage with the Audio Research logo on top, whereas the 160M has exposed transformers—if one removes its larger, “whole amp” cage cover to expose the tubes. The Ref160S also has two rear handles, which the Ref160M lacks, that make moving its 100-pound chassis easier. (For a more detailed explanation of the Ref160M/160S circuit and tube complement in the context of ARC’s development as a company, please see Executive Editor Jonathan Valin’s excellent Ref160M review in Issue 294. For more information about Audio Research Corporation as a company and its contribution to the audio arts, please refer to the ARC section in The Absolute Sound’s Illustrated History of High-End Audio, Volume Two: Electronics.)

Listening

Right from the start, the Ref160S had a wonderful, fluid, agile quality. Music skipped along with engaging litheness that did not immediately scream “classic tube amp,” in the sense of imparting a slight sluggishness on transients and some looseness in the bass. Actually, the Ref160S is the most powerful, nimble, and neutral-sounding tube amp I have had in my system. (For twenty years, until 2009, I used to run mostly new [not vintage] tube preamps and power amps exclusively.) The Ref160S combines just a touch of warm-side-of-neutral tonal balance with remarkably low—for a powerful tube amp—underlying noise, so it joins a group of tube gear from brands such as VTL, VAC, Lamm, Ypsilon, and Atma-Sphere that bucks classic tube amp sound in this regard.

Ref160S rear cover

In keeping with tubes’ typical strengths, the Ref160S had both midrange resolution and 3-D depth—both of the larger soundscape and of individual images—in spades. Though not quite as extended at the extremes as some good solid-state amps, it also expanded midrange resolution to the immediately adjacent parts of the frequency spectrum—to a degree that helped everything sound more realistic and less obviously “tube-processed.” Mind you, the Ref160S’s top end was a little softer than I am used to from the solid-state amps (Gamut, Constellation, Hegel) I have been recently using, but I did not get the sense that I was missing much sonic information when I considered the whole picture. In fact, the Ref160S reproduced the gestalt (as TAS founder Harry Pearson liked to say) of a full orchestra in a way that made me think, “Wow, that gets a lot of it right!”

It may seem like a conundrum, but the Ref160S had such a low noise floor and its image boundaries were so free of “electronic etch” or “fizz” that its upper frequencies might strike some listeners as missing the last bit of extension and information, compared to certain other amplifiers. But the Ref160S actually made music sound more lifelike, to my ear, than most other amplifiers in terms of its refined image outlines and lack of electronic grain. Maybe it was the sense of continuousness that tubes bring to bear, or the midrange lucidity, or the sense of physical presence, or the wonderful musicians-in-a-hall effect with their trailing tails of notes lingering in space a bit longer (all of which the Ref160S does so well) that contributed to an overall “reminiscent-of-live” impression. Because of this truly fine realistic quality, I was motivated to revisit some of my classical LP collection: the Poulenc Concerto for Strings, Tympani, and Organ [Erato], Canteloube’s Songs of the Auvergne [EMI], and Mozart’s Concerto No. 21 in C Major [Phillips] were reproduced with remarkably natural-sounding details and immediacy. I found new aspects of the performances’ phrasing and developmental arc—new “musical meaning,” if you will—with the Ref160 in play. (Choreographers Glen Tetley [Voluntaries], Leslie Jane Pessimier, [Les Chansons] and Jiří Kylián [Petite Mort] used the music listed above, respectively, to create wonderful neo-classical dance works, by the way.)

Pop and rock had forward momentum in a parallel to the lucid gestalt in classical music. There was plenty of transient snap and power to give well-recorded drum kit, for example, the sense of acceleration that well-recorded drums contribute to the mix. I didn’t hear the Ref160S’s musical appeal across different genres as overtly euphonic as such; rather, the Ref160S simply brought out elements in recordings that illuminated the artistic expression inherent in music more readily—provided the recordings had decent performances and were well recorded in the first place, of course. It was as if the musicians had a particularly good night at the concert hall, club, or recording studio. We have probably all attended a live performance on one evening and then heard the same group or orchestral program again on another night and regarded one evening’s performance as better than the other. The players were clicking more with each other or the singer was in particularly good voice or the sound engineer got the levels and microphones’ phase-matching right. The Ref160S seemed to have the effect of making home listening sessions come closer to a superior evening’s performance. When one of my long-time audiophile friends said upon hearing a few cuts through the Ref160S, “Wow, the music sounds really alive—I could easily live with that amp,” I got it.

The Ref160S had a very deep soundstage, the deepest I have heard in my system. Front-to-back layering was continuous and closer to real life than many amps can muster, especially amps of the solid-state variety. Images within the soundscape were fleshed out as more completely formed sound sources created by real people and instruments in space, rather than as flat cutouts or bas-relief tableaux. The front of the soundscape was moved more forward than I am used to, so this—combined with slightly narrower soundstage width—created an overall stage that was sometimes closer to a cube in shape than to a rectangle whose width is greater than its depth. I suspect some of the amp’s slightly narrower soundstaging could be the result of the Ref160S being a stereo amp rather than a monoblock. (All things being equal, a pair of monoblocks tend to cast a wider soundstage than the equivalent stereo version.) Also, I believe the Ref160S is meant to be paired with an ARC preamp, like a Ref10 or Ref6SE, which themselves recreate very wide, expansive soundscapes. (Unfortunately, an ARC preamp was not available during the review period to test this hypothesis.)

Bass was deep reaching and powerful. The Ref160S’ plumbed the depths with ease, not exactly a typical tube amp’s forte, especially when one considers the speaker I used was the YG Sonja 2.2, which generally fares better with a high-current solid-state amp. While not quite matching the speed and definition of some solid-state amps, the Ref160S had the best bass pitch definition and stability of any tube amp in my system. Dynamics were also very good, both macro and micro. The big, meaty sound the Ref160S produced stemmed, in large part, from its ability to track bass-laden dynamic peaks with sustained control. The Ref160S never clipped or showed signs of strain while in ultralinear mode. It did lose control and clip, however, on the big orchestral stuff while in triode mode (70Wpc).  I think most folks who listen in triode mode would presume it is better suited to smaller, less demanding music (or to an easy-load speaker). Speaking of triode and ultralinear modes, I did nearly all of my listening in ultralinear. While the triode mode did offer some additional warmth and intimacy on smaller-scale music, I didn’t find the difference compelling enough to be worth switching back and forth between the two modes on appropriate music selections. On the whole, I found ultralinear to sound tonally closer to neutral and more dynamically responsive.

The Ref160 gives off a lot of heat, but that comes with powerful tube-amp territory. ARC uses cooling fans to keep operating temperatures within optimal range and extend tube life. Since I placed the Ref160S in front of my equipment rack to make connecting it to and from my system easier, I did hear the fan during very quiet music passages, even with the fan speed set to low. I believe most users would place the amp in a more room-friendly position, and that would, no doubt, be farther away from the listening position. Let me add, the Ref160M/S aesthetics are a welcome change for ARC whose typical look has tended to be more industrial and functional. I liked the see-through faceplate, but I turned off the lighted VU meters, as I found them to be a little distracting. A friend thought they looked really cool and wanted to see them with their light level all the way up. (There are three levels plus off.)

Conclusion

The winning combination of a low noise floor, which allows details to emerge in an unforced way, and very high levels of image solidity, which produces a closer-to-live listening experience, is central to the Ref160S’s appeal. Add in uncommonly good bass presence and dynamic control, and you have a tube amp that goes a long way to furthering the strengths of valves while mitigating their typical weaknesses.

To my mind, the Ref160S doesn’t try to sound like a solid-state amp as such; it is, rather, a high-quality amp in its own right, and can outperform most solid-state designs in depth layering and musical fluidity. If you feel like venturing into the glories of tubes or continuing your tube amp adventures on a different plane, consider the Ref160S. It is highly recommended.

Specs & Pricing

Tube complement: Two matched pairs KT150; two 6H30 per channel
Power output: 140Wpc (20Hz–20kHz)
THD: Typically 1% at 140 watts, below 0.04% at 1 watt, 1kHz
Power bandwidth: 5Hz to 70kHz (–3dB points)
Frequency response: (-3dB points at 1 watt) 0.5Hz to 110kHz
Input sensitivity: 2.4V RMS balanced for rated output
Gain: 25.5dB into 8 ohms
Input impedance: 300k ohms, balanced; 100k ohms, single-ended
Output taps: 16 ohms, 8 ohms, 4 ohms
Damping factor: Approximately 14
Overall negative feedback: 14dB
Slew rate: 13 volts/microsecond
Rise time: 2.0 microseconds
Dimensions: 19.0″ x 10.25″ x 21.5″ (with handles and connectors: 24″)
Weight: 100 lbs. (net)
Price: $22,000

AUDIO RESEARCH CORPORATION
6655 Wedgwood Road North, Suite 115
Maple Grove, MN 55311
(763) 577-9700
audioresearch.com

Associated Equipment
Analog source: Basis Debut V turntable & Vector 4 tonearm, Benz-Micro LP-S MR cartridge
Phonostage: Simaudio Moon 610LP
Digital sources: Hegel Mohican CDP, HP Envy 15t running JRiver MC-20, Hegel HD30 DAC
Linestages: Ayre K-1xe, Hegel P30, Constellation Audio Virgo III
Integrated amplifier: Hegel H390
Power amplifiers: Gamut M250i, Hegel H30
Speakers: YG Acoustics Sonja 2.2, Raidho TD1.2, Dynaudio Confidence C1 Signature
Cables: Shunyata Sigma signal cables, Nordost Heimdall 2 USB, Shunyata Alpha S/PDIF and AES/EBU, Shunyata Sigma NR and Omega XC power cords
A/C power: Two 20-amp dedicated lines, Shunyata SR-Z1 receptacles, Shunyata Everest 8000 and Typhon power conditioners
Accessories: PrimeAcoustic Z-foam panels and DIY panels, Stillpoints Ultra SS

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Original Resource is Articles – The Absolute Sound