PS AUDIO Gain Cell DAC and M700 monoblocks ~ The Sound Advocate

Stellar performances accomplished: The PS Audio Gain Cell DAC and M700 monoblocks are thoroughly examined !

It’s a bit hard to believe (while blatantly showing my age) that PS Audio was initially launched back in 1973, and had only one product: a phono preamp. This preamp was a standalone phono stage (turntable preamp). It was this phono stage that first brought Stan Warren and Paul McGowan together as partners.

This initial phono stage was designed as a broadcast piece of equipment under commission to a local radio station. It sounded quite good, which eventually brought about the beginnings of P.S Audio’s venture into the world of high-end audio, which was just starting to bloom here in America.

STELLAR GAIN CELL PREAMP/DAC

PS Audio Stellar Gaincell DAC preamp and M700 monoblocks

In 1983 they launched the first external audiophile DAC, which most people at the time were not even aware of. As their product lines grew exceptionally well, PS Audio, then as is now, became known for excellent sounding audio components at prices that at times can belie one’s imagination.

Research on the Gain Cell Preamp/DAC started in 2000, as PS Audio was trying to take a zero-loss analog preamp and add it to a fine-sounding DAC. In theory, this to me is the ultimate component. A State-of-the-Art preamp and DAC in one chassis. But the question, in this case, was to get the highest sound quality in a complete analog control center along with a digital to analog converter in the same box at a reasonable price. One could quite rightly ask, “Why not go all the way with separates…if it costs a bit more, so be it? (Personally speaking, I wholeheartedly endorse the former design philosophy of a control preamp/DAC within a single chassis, be it at any cost, if the unit is astoundingly well built with a ‘stellar’- no pun intended, sound quality. I do not need so many components occupying my control rack).

Keeping price and performance in mind, as the design matured, PS Audio mated the digital circuitry with their proprietary fully-balanced Class A (Gain Cell) analog output stage and a custom-configured FPGA – (Field Programmable Gate Array) – for the input stage. The idea behind the Gain Cell control unit is to maintain signal integrity without putting transformers, stepped-attenuators, ladder networks or relays, etc. between the DAC and the pre-amp output: it simply varies its gain based on user-defined parameters; in this case, a volume control.

As it turned out, PS Audio took almost all the features and functions any audiophile could ever imagine in a preamplifier and modern DAC and put together the Stellar Gain Cell Control Unit we are looking at here. It is a zero-loss, fully balanced, pure, analog control center combined with DAC attributes that are rarely found at this price level. Its fine DAC is its main star.

Aside from the previously mentioned and obvious advantage space-wise of a component such as this, the Stellar Gain Cell DAC/Preamp contains some profound features and functions that are both ergonomically intelligent and easy to use.

Even as of today, it is quite hard to get an exceptional analog preamp and DAC combined into one main chassis. Although there are a few high-end units out there, from my point of view, hardly enough as I find it a worthwhile and highly convenient and intelligent merge of components.

M700 CLASS A/D MONOBLOCKS

PS Audio Stellar Gaincell M700 monoblocks

With the advent of the sleek, gorgeous looking Stellar M700 monoblock amplifiers, the companies design essential again was to produce a majestically musical sounding power amplifier that could compete, no less beat any high definition audiophile amplifier at the $5,000 price point.

PS Audio designer Darren Myers, threw the ball in a somewhat new, but challenging way—a hybrid that would combine the best of today’s technology along with the latest version of “a proprietary, fully differential, zero feedback, discrete, class-A MOSFET circuit”—thus using it to drive a Class-D power module from the Danish ICEpower company. (You can read about an abundance of excellent Class D amplifiers in last year’s amplifier reviews in The Sound Advocate.

In the past, Class D amplifier designs have had some inherent problems common to this technology. This recently has been overcome. If you have had any good, prolonged and discerning listening experiences with some of the most current high definition Class D power and integrated amplifiers now being offered to the discerning audiophile, one can say in the most uncertain terms that when designed correctly, many of them can offer outstanding sound quality and at reasonable prices. Some current examples being from Wyred4Sound, Peachtree Audio, Channel Island Audio and Bel Canto, just to name a few

As for the M700, in theory, this amplifier should provide a neutral sounding power output stage. Many, if not all, would be happy with neutrality: never adding nor subtracting from its starting point. In the case of the Stellar Gain Cell, P.S Audio has gone a bit further than many others above; namely by designing a hybrid or what P.S Audio calls the Analog Cell.

This ‘Analog Cell’ is Class A and built with the MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistor; a semiconductor device which is widely used for switching and amplifying electronic signals in the electronic devices. Paul McGowan (PS. Audio’s co-founder) likes to think of this new “class” of an amplifier, Class AD.

The M700 is a single-channel hybrid Class A/Class D power amplifier that offers a huge 350 watts output into eight Ohms and 700W into four Ohms. As such, this amplifier has a stunning reserve of power and it can drive just about any speaker that it may be mated to with glorious results. It’s the same physical size as the GC-DAC (17x12x3 inches) and has a nice, streamlined weigh in at about 16 pounds.

The unit is offered with RCA and XLR inputs and has a measured THD of less than .02 percent at 1KHz, 1W/4 Ohms. The circuit design utilizes the balanced, zero-feedback, Class A MOSFET-based Analog Cell for its input stage. Myer’s involvement in the Stellar GC-DAC and M700 design saw himself, along with McGowan, focused specifically on the tone of the amp to project a hint of warmth along with a highly neutral sense of audio resolution; which it does show off in spades.

Both of these units are beautiful, and quite glorious to behold. The question now is do they measure up in their subjective sound quality as described by the designers? Let’s explore further.

SOUND – STELLAR PREAMP/DAC (GCD)

Of the few, high-quality preamp/DAC combos available in this price range most of them use a potentiometer to control the volume of the signal. The potentiometer has been the workhorse of control and position systems for over a century. Advancements in potentiometer manufacturing have made them more reliable, more accurate, and more cost-effective than ever before. However, they may tend to add some ‘coloration’ to the sound as well as having channel imbalances of up to 2 to 3db.

The Gain Cell replaces this component which incorporates impressively accurate channel-matching and sonic transparency. The Gain Cell also outperforms most IC volume chips that tend to have low quality, integrated op-amps in their signal path. The unit has a few options to sort through—user-selectable digital filters, renaming of inputs, channel balance, display brightness, and timeout, etc.

The Gain Cell is also unique in that it contains 3 choices of filtering a user can try. This proved to be quite interesting, to say the least, particularly when doing critical listening for this evaluation.

For critical listening, PS Audio gives users three choices of filtering for its Stellar Preamp/DAC with the ‘Slow Roll-off Linear Phase’ being the default option. It is described as having a tiny loss in high-frequency extension; barely noticeable with CDs and other 44.1Khz program material as well as with higher sample-rate sources. It has scarcely any ringing and will be considered the optimal choice and most musical sounding for most users.

The second filter extends the high frequencies somewhat with a touch more ‘ringing’ as well. It may be preferred for most 44.1Khz material.

The last choice is a Fast Roll-off Linear Phase filter and although this filter may measure the best in a laboratory, PS Audio proclaims it to be the most analytic of the three. As it turned out, after experimenting with these filters for not more than a half-hour, it was decided that the default filter was indeed the best choice in my testing.

The biggest benefit of digitally controlling gain is that channel matching should be good and, in this case, the Stellar Gain Cell is quite outstanding. After installing the GCD in place of the excellent Peachtree Audio Nova 300 preamp section, then routed into their M700 monoblock’s, an unmistakable gain in music and instrumental locational imaging and sound stage precision was immediately noticed. This cannot be overstated as such. The channel matching on some high-end preamps can sometimes leave a bit to be desired, hampering your speaker’s abilities to give you an exact, holographic stereo image, particularly center imaging which is what immediately jumped out to me upon listening.

Full orchestral and vocal program material engaged was able to implicitly place instrumentalists and soloists exactly in their respective places on the soundstage, quite naturally depending on how the sources were recorded. But I intended to take this one step further. I ripped to CD a digital wave file mono signal of pink noise and music. The Stellar Preamp/DAC (and D700 monoblocks) gave an exemplary display of center imaging and amazingly accurate soundstage locational effects.

I did this over some time with at least four pairs of loudspeakers mated to the PS Audio Gain Cell Combo. All performed exquisitely and you can be sure, if there is any kind of stereo imbalance in your preferred system and or loudspeakers, you can immediately bypass the Gain Cell pre/power combo and look elsewhere—be it up or down the stream of your system.

I’ve been privileged to have the Gain Cell/DAC in my system now for quite a few months. The Gain Cell Pre/DAC was partnered not only with the M700 but also with CIA Audio’s C100s stereo amplifier as well as the Wyred4Sound mAMP monoblocks as a fine, solid comparison.

As a control unit goes, this streamlined P.S Audio was simply audacious in how it just appeared to be “not in the system” while allowing all the most majestic program material I could throw at it just come to life and breathe in my listening room. Classical music, pop, acoustical, opera, and the most finely recorded discs– live and recorded streaming and CD ripped concert performances were all put to good use while pushing the limits as to the huge yet discerning wall of sound offered. (I was doing streaming with the latest Innuous. Zenith Mk III player/streamer; review forthcoming)

One is immediately aware of the close to absolute neutrality the GCD sounds with the many of these program sources. At this price, the P.S Audio GCD is quite a wonder in the high-end audio field. The control end of the GCD was quite fulfilling to use as its remote was highly intuitive and forthcoming. Again, imaging stability and front to back depth were empirically confirmed while the units forthright, detailed, and imminently “even” sound presentation was second to none. Things remained established and competent when connecting the GCD to the M700’s as well as with the Wyred4Sound and CIA amplifiers mentioned above. Differences in the latter Amplifier’s sound character as compared to the D700’s were small and will be contrasted further on.

CONSIDERATIONS?

Initial listening impressions with the GCD showed an impressive amount of musical detail, fine soundstage width, and a profusely stable amount of stereo image localization. (the latter being the forte of the GCD). So much so good.

Later on, with more concerted auditioning, I did come to notice a tiny bit of ‘sharpness’ on transients emanating on string and wind instruments with certain loudspeakers involved. This was particularly evident with the Quad ESL 63’s as well as the Spendor BC1 loudspeakers. However, this inevitably varied when other speakers were involved, mainly the superb Aerial Acoustics 6T which has an enviable high-end response compared to many loudspeakers within and above its price point.

Further examination and comparisons could have pointed to the DAC contained within the GCD which displayed a tiny amount of image width shrinkage as compared to some other DAC’s that I compared in the listening sessions. On the other hand, this appeared to be mostly rectified upon changing loudspeaker cables and/or interconnects. Once again, we find component and cable matching to be of the utmost importance when evaluating any part of the audio chain. In the case of the GCD, it less favored Wireworld’s Eclipse 8 in favor of the Inakustik LS-4004 or even more so, the newly released Silversmith Audio ‘Fidelium’ cables. One could, therefore, state quite adamantly that cable experimentation is mandatory with P.S Audio’s GCD. When you find the right match, you will be supremely rewarded!

SOUND-M700 MONOBLOCKS

Upon first setting up and turning the volume up on the M700’s, one is overwhelmed with the sumptuous amount of power these units exhibit. The M700’s Class A/D design was by no means self-effacing with its 350W into eight Ohms and 700W into four Ohms. It began and adamantly sustained the full extremes and total weight and richness of the program material it was reproducing.

In the case of the M700, the designer was able to inject a snippet of ‘warmth’ without sacrificing resolution and neutrality. There is no doubt in my mind that P.S Audio has overshot their goal here as these monoblocks produce groundbreaking audio reproduction in just about every way possible.

Large scale orchestral works, acoustical pop recordings, operatic vocals, and just about every well-recorded piece of music that these amplifiers saw was reproduced with truly breathtaking clarity, intense yet smooth transients, a full-bodied midrange, and a superbly nuanced and self-effacing treble range. The amps are exceptionally quiet–even more so when used with Inakustik’s groundbreaking power station.

If your loudspeakers have a response that can go way down in the frequency spectrum, expect huge bass drums to be reproduced with the utmost precision, tightness, and glorious resonance within the back depths of the soundstage. I will say that there is not a loudspeaker made that will not be impacted by the magnificence of the D700’s bass performance, while with its extravagant power output, it lets you feel that you are ensconced in the sound and the venue that the recording was made in your listening room. This is one hell of a show, indeed!

As with the GCD, channel balance (while not measured) was spot on as it displayed the twin channel stereo locational effects with extreme accuracy. Some reviews of this amp have been critical of its high-frequency response but don’t believe it. If you’re using good, well-recorded, or live program sources, the M700’s will show the sublimely “minuscule’ and silky roll off of the extreme high frequencies that massed violins should display in a confident acoustic of the recording locale. Horns, bassoon, and flutes are reproduced with subtle shadings and layers within the depth of the stage and are tonally correct, neutral, and quite naturally extended. As should be obvious from that statement, I’m assuming your loudspeakers mid- to high-frequency response is not acidic, stinging, or peaky in any way and the room acoustics are generally close to neutral regarding reflections and overall bass response.

As previously mentioned, Paul McGowan has stated that the voicing of the M700 involved comparisons with PS Audio’s flagship amplifier,the BHK Signature 300, which uses tubed input circuitry. Having not heard the Bascom King units, my listening tests do confirm that there is a touch of tube sound to be found in the M700’s, midrange as they are non-fatiguing and seem to offer a generous, blossoming sound to the music it is presented with. As an interesting comparison, the Channel Island Audio’s C100S 100-watt power amplifier did tend to sound a bit more like a tubed power amplifier in the midrange in some ways.

However, continuing with a comparison between these two units, I found them to be quite close in that quality and their overall sound attributes. Although the C100S did have a bit more of that “tube” etherealness not quite matched by the M700’s, I must say that the exquisitely designed and exuberant power stockpile of the M700’s along with that touch of silky warmth in its overall balance gave me a sumptuously reassuring and glorious display of ambiance and fundamental harmonic accuracy that keeps one always coming back to the M700’s.

Currently, I have been auditioning the M700’s with the following loudspeakers: Aerial Acoustics 6T’s, the latest Audio Note (UK) AN/ED loudspeakers, (review coming), my standard vintage Quad ESL 63’s and Spendor BC1’ and the awe inspiring Graham Audio BBC LS5/9. All of them have been able to glorify the design aspects and subjective sound reproduction of the M700 monoblock amplifiers in every way within my preferred listening room.

CONCLUSIONS

The complexity of class D amplifier design has its innumerable rewards. The good side of a class D audio amplifier is higher efficiency, less heat, and less weight. Very little energy gets wasted as heat. Thus, the amp requires less heat sinking.

With more improvements on the horizon, class D amplifiers are becoming commonplace in many high-power applications. The advantages of greater efficiency, the finest audio performance, and space and cost savings will continue to be the main drivers of the increasing use of these amps.

have no qualms in proclaiming, particularly now with a plethora of high definition, value-oriented electronics available to the audio enthusiast, that The P.S Audio Stellar Gain Cell DAC/Preamp and particularly, the M700 Monoblock amplifiers are one of the finest set of components available to the “High End” audiophile consumer at this moment; especially in light of their resounding price points!

No doubt, Messrs. Myers and McGowan have used their engineering skills and even more so– their fine musical ears and knowledgeable backgrounds when designing the Stellar Gain Cell combination.

The Stellar GCD is a fine sounding, preeminently convenient preamp/control unit that contains a top-quality DAC; ultimately bringing forth fine stereo image localization and stability from the loudspeakers employed in the listening sessions as well as good depth perspectives and ambient detail. In some cases, it just barely conceded some image width and a tiny tilt up at the high-frequency extremes. In those rare situations, this was undoubtedly nullified by the choice and design of the cables used in one’s existing system. As is common, discerning cable matching will be most advantageous.

As for the M700 monoblocks, there is no need to mince words here. Once auditioned in your system you will be captivated by their alluringly natural, neutral, and just plain outstanding sound quality. The huge amount of power they are endowed with provides sound with breathtaking exhuberence when mated with almost any loudspeaker it is married to. These units are meticulously built and sound great right from the get-go. The M700 monoblocks are a standout product that deserves all the praise one can give to it. Congratulations to P.S Audio on two Stellar components!

REVIEW SYSTEM: Analog– Rega RBRega Planar 6 Turntable/RB300 arm / Ortofon Cadenza Bronze cartridge ● Digital- Audio Note (UK) CD 3.1 x/II player/DAC / Wyred4Sound 10^th Anniversary DAC/ Amplification ● Peachtree Audio Nova 300 2019 (preamp) ● Channel Island Audio’s C100S/ Wyred4Sound mAMP monoblocks ● Loudspeakers •Audio Note (UK) An-E/D / Spendor BC1/ Quad ESL 63 USA, Graham BBC LS5/9 loudspeakers ● Cables Conditioners: Inakustik AC-3500p, LS-4004 speaker cables, AC-2404 reference Air Power Cord/ Silversmith Audio ‘Fidelium’ loudspeaker cables/ Wireworld Eclipse 8 interconnects & Electra 7 power cords/ Audio Art 1 e” AC Power Cord.