PS Audio Stellar Gain Cell Digital-to-Analog Converter and Stellar M700 Mono Amplifiers

"The PS Audio Stellar DAC and M700 amps took my system to a level that, with some recordings, was eerily close to the real thing."

by Guy Lemcoe | June 22, 2018

S Audio began, literally, in former disc jockey Paul McGowan’s living room in the town of Santa Maria on California’s Central Coast 44 years ago, when waterbed installer Stan Warren (the "S" in PS Audio; Paul was the "P") paid a visit. Both were hi-fi tinkerers who, in 1974, after putting their heads and very limited funds together, launched PS Audio’s first product, a $59.95 phono stage. So confident were they in their product that they offered a then-unprecedented money-back guarantee.

Prices: Stellar Gain Cell, $1699; Stellar M700, $1499 each.
Warranty: Three years parts and labor.

PS Audio
4826 Sterling Drive
Boulder, CO 80301
(720) 406-8946
www.psaudio.com

That initial offering was followed by the PS IV line-stage preamp and Model One power amp. The rest, as they say, is history. Following the startup, PS Audio released, to positive industry-wide recognition and consumer acceptance, more power amplifiers, several preamplifiers, integrated amplifiers, and digital products. Seven years after co-founding the company, Stan Warren left to start Superphon. Bob Odell, of Harman Kardon, took Stan’s place. Ten years later, in 1990, Paul McGowan left to team up with the late Arnie Nudell of Infinity Systems to form Genesis Technologies, and PS Audio was sold to Steve Jeffery and Randall Patton. Deteriorating financial conditions forced the closure of the company in 1997.

A year later, McGowan again assumed control of PS Audio, with a manufacturing emphasis on AC power conditioning and the release of the Power Plant P300, a product that created an entire category of power-regenerating components. Today, PS Audio once again enjoys a well-deserved place in high-end audio, offering a full spectrum of audio and power components, cables and accessories. Having met Paul McGowan at past CESes, I can attest to his outgoing personality. He’s enthusiastic, quite the talker, and has a wry sense of humor. His company reflects this persona by being extremely user-friendly -- PS Audio’s customers (and other audiophiles) can follow the company through online forums, daily blogs, live videos, a monthly newsletter, and the Copper e-zine.

This review focuses on PS Audio's budget-conscious Stellar Gain Cell DAC and M700 mono amplifiers. Over two years in development, PS Audio's Stellar line seeks to make available equipment that is affordable, attractive and solidly built; but above all, it has to sound good. Affordability being a relative concept, I’ll let the reader decide if the stated prices fit his or her definition of the term. (To make a buying decision even easier, PS Audio offers a discount if the Gain Cell DAC and either the stereo or mono amps are purchased together. In addition to that, PS Audio has a unique trade-up policy, the details of which can be found on their website.) As far as looks and build quality go, PS Audio scores a perfect 10. As to the products' sound, read on.

The amps and Gain Cell DAC came double-boxed in sturdy, no-frills cartons. Due to the M700's light weight (I could easily lift one in each hand), unpacking and setting up the pair of amps was easy. It was just a few minutes before I had them installed in my equipment rack. Ditto the Gain Cell DAC. With a height of just three inches, the products maintain a low profile (no pun intended) yet manage to fill the rack’s shelves with their 17" width and 13" depth. The design is svelte and minimalist, which I found aesthetically pleasing, especially with the backlit, blue power-status indicator/logo buttons. Each unit comes with a six-foot power cord and a well-written manual.

The M700 monoblocks represent the embodiment of designer Darren Myers’ dream of a power amplifier that's modestly priced and offers state-of-the-art sonics. How did PS Audio achieve this? As stated in their literature:

Rated at 350 watts into 8 ohms and 700 watts into 4 ohms, the M700 combines the best of two worlds: ultralinear, high-current, Class D technology for the output stage; a discrete, Class A MOSFET based Analog Cell for the all-important input stage. In the M700 a unique topology called the Analog Cell has been employed to preserve the rich details found in music. The Analog Cell is a zero feedback, balanced, Class A, MOSFET input stage. The design closely mirrors the sonic characteristics of a vacuum tube and allows Myers the freedom to voice the amplifier as he sees fit. Long hours of listening and tuning sessions in Music Room One, shared by PS Audio founder Paul McGowan and Darren Myers, resulted in a sonic signature that honors the music and never draws attention to itself.

Each M700, hand-built in Boulder, Colorado, incorporates its own generous power supply and ultralinear power-amplification stage based on the class-D ICEpower module. Benefits of this configuration are claimed to be near-perfect linearity and excellent frequency extension coupled with low distortion, high efficiency and unprecedented power output. The M700 can also drive just about any loudspeaker available. Throughout the reviewing period, the amps never got more than a tad over room temperature to the touch. PS Audio recommends using the best cable you can with their products, and I did just that, with a full complement of Shunyata’s Venom interconnects and speaker cables.

With the exception of the power-status indicator on the left side (which, upon turn on, blinks repeatedly for a few seconds before stopping, indicating all is well), the front of the M700 is unadorned. The rear panel sports the main power rocker switch just above the IEC AC receptacle and, centered, two sets of speaker terminals (to facilitate biwiring), a remote trigger input and output, and single-ended and balanced main inputs. That’s it.

The front of the Gain Cell DAC features the same backlit, blue power-status indicator/logo button as the M700 along with an Input selector/Menu button just left of the 3 1/2"-wide OLED display. A large Volume control (effecting small-step changes) dominates the right side of the Gain Cell DAC, to the right of which is a 1/4" headphone jack. A smallish remote control (for which a separate manual would have been appreciated) duplicates some menu functions. In addition to acting like an asynchronous DAC capable of up to 384kH/24-bit performance for PCM and single- (64) or double- (128) rate DSD, as you might be able to guess, the Gain Cell DAC also serves as a versatile analog preamplifier, balanced from input to output. You won’t find tape outs or tone controls, though, since the objective was to offer a straight-line source selector with variable gain. The only nod to signal manipulation are the three selectable digital filters used for tailoring the sound of PCM digital audio only and absolute phase inversion.

The rear of the Gain Cell DAC is more congested with, from left to right, the main power rocker switch (above which is a fuse holder), IEC AC receptacle, four digital inputs (two coaxial, TosLink and DSD-capable USB), and I²S in HDMI form, left and right balanced and single-ended outputs, remote trigger input and output, three single-ended (whose close spacing might cause a problem with some gargantuan RCA connectors) and a pair of balanced analog inputs. The absence of a phono stage obviated the necessity of a ground lug for connection of a turntable’s ground wire.

In PS Audio's words:

At the heart of Stellar Gain Cell DAC is a stunning, Bob Stadtherr designed, digital to analog converter. Based on industry leading Sabre32 bit Hyperstream architecture, Stellar DAC features a fully balanced Class A analog output stage with multiple power supplies, independent jitter-reduced inputs, DSD, I²S, and asynchronous USB.

What is a Gain Cell? PS Audio continues:

Instead of inserting an additional level control in the signal path, the PS Audio Gain Cell relies on a different technology known as a variable gain amplifier (Gilbert Cell) . . . . The idea behind the variable gain cell is simple. Instead of adding additional circuitry to the signal path to vary loudness, the preamplifier’s actual amplifier stage varies its gain in response to the user’s front panel volume control. This method requires zero additional circuitry in the signal path, offers more than 80dB of attenuation, and if designed properly performs to the equal of most high-end preamplifiers.

Setting up the Gain Cell DAC for my system involved assigning names to its eight inputs. This job, which required repeatedly turning, pressing, turning and pressing the volume knob, infuriated this dolt, but once I discovered the secret, all went well. Inputs 1-3 are analog (Input 1 offers a balanced option), and I labeled it LP. Input 2 became SACD and Input 3 was left as a spare. Inputs 4-6 went unnamed. Input 7 is TosLink digital, so I named it CD. The last input is a USB. It should be noted that not all functions are available to sources connected to the analog inputs.

fter replacing my trusty Emerald Physics EP100.2SE stereo amp with the M700 monoblocks and Emotiva USP-1 preamp with the Gain Cell DAC, among the first things I noticed were the solidity, coherence and smooth musicality of the presentation. Those prodigious class-D amps were doing their thing, lending a strong foundation to the bass, above and beyond which extended (when captured in the recording) a huge soundstage. The mids and highs were irreproachable, landing easy on the ears. With recording after recording, I swear I could hear previously unheard performance details.

Something good was happening, so I just sat back and enjoyed the show. With the nearly five-decade-old LP King of the Bayous [Arhoolie Records 1052], rarely have I heard this upbeat music sound as tangible as with the PS Audio gear. Clifton Chenier was in the room with me, accordion in hand, along with the rest of his band. Unfortunately, so was the groove "swish" accompanying the less-than-ideal pressing. With the low noise floor of the PS Audio electronics, it was easy to hear the differences in the two Houston studios used for the recordings: Jones (side 1) and Gold Star (side 2).

On a more austere note, in the late Michel Chapuis’s interpretations of Nicolas De Grigny’s Le Livrè D’Orgue Tome II (Les Hymnes) on a pristine, four-decade-old LP [Astree AS 9], the sound and mechanics of the pipe organ along with the ambience of the Cathedral of Saint Christopher in Belfort, France, where the recording was made, were captured vividly. When I closed my eyes, I could imagine myself within its sandstone walls, the dulcet tones of the 266-year-old organ wafting over me. The speed of and control over extreme low frequencies were demonstrated by the heart-stopping bass "thumps" heard on track 5, "Laptimevinmeri/Laptev Sea," from the Finnish electronic music project Pan Sonic’s 2007 album Katodivaihe/ Cathodephase (16-bit/44.1kHz FLAC).

Returning to more conventional music, I cued up You Want It Darker [Columbia 88985365071], Leonard Cohen’s final album before his untimely passing in late 2016. On the title tune, the imaging was spot on, the PS Audio components placing the chorus clearly behind the speakers with Cohen precisely centered several feet in front of the voices. It’s to PS Audio’s credit that the words to the songs were easily understood as the softly spoken, near-mumble quality of that deep baritone voice often makes the lyrics unintelligible.

After reinserting the Emerald Physics EP100.2SE stereo amplifier into the chain, the most immediate thing I noticed was the need to increase the volume setting in order to get the same level as that reached with the M700s. Those 350 on-demand watts per channel do make a difference. With the Emerald Physics amp, I did notice a very slight narrowing of the soundstage and I thought I could hear a slight softening of the mids and highs, although I cannot make a definitive statement on this. In fact, I find it difficult to make any definitive comparative statements regarding the sound of the two amplifiers. They are that close. Perhaps the explanation is that they both use Danish ICEpower modules. Both provided ample power to pressurize my room when called for and both seemed equally able to plumb the lowest bass frequencies without feeling any pain. If anything, the Emerald Physics EP100.2SE summoned up more robust, if less controlled bass than the M700s, as evidenced on the Pan Sonic track cited earlier. As for the mids and highs, well, these are not tube amps and they did present, in my experience, a more analytical, less euphonic sound in this range than tubes (the Emerald Physics EP100.2SE less so). I personally prefer this sound.

Let me repeat: At no time did either of these amplifiers sound etched or cold and emotionless. Instead, they laid bare the defects, if any, in the source material. With due credit to computer-science lingo, the old maxim "Garbage in, garbage out" rang true throughout my listening sessions. Well-recorded material sounded transcendent. Not-so-well-recorded material sounded, uh, not so well recorded. If pressed, I would characterize the M700s as polite with attitude, compared to the slightly bold-yet-reserved sound of the EP100.2SE. Which type of sound you’ll prefer may be an indicator of whether you like your coffee black or with cream and sugar. My experience with class-D amplification so far has been a positive one -- so much so that I cannot understand such amps being sometimes disparaged in the press. Both of these amps produced sound I could easily live with.

I was curious to hear and compare the sound of the Gain Cell DAC to my AudioQuest DragonFly Black (with latest firmware upgrade) and TEAC UD-501 DACs. The DragonFly, nestled into my computer’s USB port, was connected to the Gain Cell DAC by a 3.5mm mini-jack male RCA stereo cable. The TEAC took the signal from USB on the computer but was plugged directly into the USB input on the back of the UD-501. That signal (with upconversion turned off) was then routed to the Gain Cell DAC with Shunyata RCA cables. The results of this listening event were informative but not unexpected. The DragonFly proved to be a silly-good DAC for the money. And it’s portable! What it gave up in terms of bass oomph and air, it made up for in terms of resolution and presence. Even though it made for fun listening, it was no match for either the UD-501 or Gain Cell DAC. Discerning differences in sound between the TEAC UD-501 and the PS Audio Gain Cell DAC proved to be more of a challenge. Both provided sound that I could happily live with. When I switched on upconversion in the TEAC, I thought I could perceive a slight improvement in the sound -- a smidgen more there there, greater physicality, if you will -- but this could be projection or illusion on my part. It really took some concentrated listening to expose any differences. Ultimately, I found this type of comparative listening far from enjoyable. I was losing sight of the forest by focusing on the trees.

What I found very enjoyable was Tidal’s hi-fi streaming upgrade option. Keith Jarrett’s Standards Vol. 1 proved useful for comparisons between streaming audio (Tidal 24 bits/96kHz), CD [ECM 1255 5182270] and LP [ECM 1255]. I found very little, if any, difference in the sound of a selection streamed or played on CD. Only when compared to the LP could I discern a slight relaxation to the sound and a cloaking of the performers in a more palpable ambient field. With streaming audio, in direct comparisons using Jonny Greenwood’s sublimely unsettling music to the 2007 movie There Will Be Blood, I preferred Tidal’s 1.4Mbps lossless streams to Spotify’s 320kbps lossy ones. Though Spotify got it 80% correct, Tidal’s hi-fi mode bettered it for dissecting the dense, often caustic string orchestrations. In a word (well, three words), I got it.

I’m not going to retire my turntable anytime soon. But as streaming audio continues to improve, I find myself troublingly attracted to it. The aspect I find troubling is the way it has changed how I acquire and listen to music. I don’t look forward to visits to the local used record stores or add items to my eBay vinyl watch list as regularly as I used to. I own all the CDs I’ll probably ever need or want. Now, I sit in front of my laptop, open Tidal, enter an artist’s name in the search box and click the mouse. Depending on the artist, I’m immediately presented with a few to dozens of album titles that I can easily add to my online music library and listen to in never less than CD-quality sound -- and now, with MQA, often better. Listening to music was never this easy and, unfortunately, I’m finding it quite addicting.

I’m also not retiring my Emotiva USP-1 preamp anytime soon. It proved to be an overachiever upon its introduction eight years ago and continues to impress to this day. Did it offer the apparent resolution of the Gain Cell DAC? Maybe. Did it provide as tactile a three-dimensional soundscape? No. Did it have as much air in the presentation? No. Compared to the Gain Cell DAC, however, it offered a more "hi-fi" sound, in a good way, a sound I grew up with and am comfortable with. In contrast, the sound of the Gain Cell DAC was relaxed, involving and truthful to timbre. The Emotiva USP-1 was wound tighter, equally involving and explicit, though a tad less revealing of flesh on those elements involved in music’s creation. Bottom line -- of the two, the Gain Cell DAC provided more pleasant listening over the long haul.

Because I still had on hand the pair of Magnepan MMGi's that I had recently reviewed, it didn’t take me long to hook them up along with the Pioneer subwoofer for a listen with the PS Audio electronics. As I expected, the result was the sound of a match made in heaven and the attainment of a new reference, clearly demonstrating the magic found in well-designed and -executed planar loudspeakers. Listening to Bill Laswell’s In Dub (16-bit/44.1kHz FLAC) in its entirety proved revelatory. On this album of music consisting mostly of all manner of electronic percussion and electric bass, the soundstage expanded in every dimension, achieved without any loss of pinpoint image specificity. Consequently, I had oodles of fun listening for the next sonic surprise playing across the soundstage as Laswell’s bass struck its pulse amid a flurry of electronic effects.

My positive impression of the PS Audio electronics' bass authority was confirmed listening to "Against the Upper House" and "A Dangerous Road" from Laswell’s 2012 release, Means of Deliverance (16-bit/44.1kHz FLAC). The bassist’s virtuosity was on constant display as each note from the lowest open string to the highest harmonic pulled from his Warwick Alien fretless four-string acoustic bass guitar was cleanly articulated. The clarity, speed and dynamics of the Maggies made these hypnotic and immersive listening experiences. What once were perfectly acceptable presentations became exceptional ones. On certain music, such as "Untitled 6" from the Icelandic group Sigur Ròs’s 2002 album () (16-bit/44.1kHz FLAC), the breadth of the soundstage belied the size of the speakers. The soundscape was cavernous and vast, extending a few feet in front of my nose to the neighbor’s lawn across the courtyard. Demonstrating the speed and ample reserve power of the M700s, the cranking of the car engine that opens the first track on last year’s Kraftwerk release, 3-D The Catalogue (16-bit/44.1kHz FLAC), was startlingly realistic in its dynamism.

Before signing off on this review, I wanted to experiment with the use of embarrassingly inexpensive isolation devices under the M700s and Gain Cell DAC. As is well known, any change to a system will result in some change in the sonics, good or bad, so it was with some trepidation I slipped four DiversiTech MP-2E 2" x 2" composite foam pneumatic pads under the feet of both the Gain Cell DAC and the M700s. For applying this under-$10 tweak, I was rewarded with an overall positive improvement of the sonic picture, with more-fleshed-out vocal and instrumental images, increased tangibility of the soundstage and tauter bass. An ear-opening example of the finesse and high-frequency extension of the PS Audio electronics, as enhanced by the DiversiTech damping pads, were the stunningly clear textures and shimmering timbres of the innumerable unique chimes in the song "Clock Chimes in the Mist" from John B. McLemore and Tor Lundvall’s recent album Presents Witness Marks: The Music of John B McLemore [320kbps MP3 only].

Curmudgeon that I am, I’m not yet a big fan of DSD. I find the files (albums) prohibitively expensive, the catalogue choices limited and prefer not to have to hassle with the download details. I also enjoy the physical nature of a 12" LP for graphics and liner notes. Even the miniscule graphics and notes accompanying CDs give you something to hold in your hands. I find downloads impersonal and sterile, distancing me from the music. Having said that, I must say the few native DSD files I sampled sounded exceptional on the Gain Cell DAC. Any differences between it and the TEAC were inconsequential.

Of the nits I found to pick (this is a review, after all), one was ergonomic: I wish the remote control were larger. On more than one occasion, it flew out of my hand when I picked it up. Also, due to my ham-fistedness, I occasionally hit the wrong buttons when changing volume. Phase is directly above the + control and Filter is directly above the - control, and I often hit the wrong button. Additionally, it was too easy to inadvertently change the channel balance with careless button-pressing. I would also have liked to see upsampling of input data, which the Gain Cell DAC’s big brothers do automatically. The native 16-bit/44.1kHz PCM streams sounded fine with the Gain Cell DAC, but lacked that last bit of resolution and air I heard from lossless streams upsampled (to 192kHz) from the TEAC UD-501. Finally, I missed a mono switch.

But overall I could not fault the sound of the Gain Cell DAC -- its neutrality and honesty were captivating, leading to compelling listening. During my time with it and the pair of M700s, I always felt they had total control over whatever music was thrown at them, in whatever format. From the understated nuance of an unaccompanied lute to the bombast of a symphony orchestra going full tilt, the laid-back drive of dub or the pulse of electronica, I not once felt deprived of any of the music’s emotion, rhythm, dynamics or detail. Whether using planar, stand-mounted or floorstanding speakers, I knew I would be rewarded with music free of noise, artifact or boredom. Used together, the Gain Cell DAC and M700s represent an intelligent, cost-effective entrance into high-end audio’s top tier. Granted, there are components out there costing much more offering arguably better sonics, but I seriously doubt any music lover would be unhappy with this duo's capabilities, sonic or otherwise.

he PS Audio Stellar Gain Cell DAC and M700 mono amps took my system to a level that, with some recordings, was eerily close to the real thing. Paul McGowan and his crew in Boulder should be beaming with pride over the superlative performance of these components. Those making a first purchase or those seeking to upgrade must audition these electronics or risk having spent hard-earned money foolishly elsewhere. Add a pair of synergistically matched speakers (this is where a good local dealer comes in) and a decent source and you’ve got yourself a damn fine music system that will bring a smile to your face each time you fire it up. As for me, sonic revelations surfaced regularly with these elegant components, illuminating more of a given musical selection’s nuances and soul.

It's good to know that Paul McGowan is still at it -- making musically significant electronics that don't cost a king's ransom. If I were an audio retailer, I’d put together systems consisting of a pair of Magnepan MMGi's, the PS Audio Gain Cell DAC and a pair of M700s and a subscription to Tidal, and watch them fly out the door.

Associated Equipment

Analog: Audio-Technica AT-1240 turntable; Corus Black, Dynavector DV-20X2H and Ortofon 2M Blue  cartridges; Pro-Ject Tube Box S phono stage.

Digital: Sony DVP-NC685V CD/SACD player, Teac UD-501 and AudioQuest DragonFly Black digital-to-analog converters, HP Elite Book 8470p laptop running Windows 10 Pro and foobar2000, Tidal and Spotify streaming services, Shunyata Research Venom USB cable.

Preamplifier: Emotiva USP-1.

Power amplifier: Emerald Physics EP100.2SE.

Loudspeakers: Magnepan SMGa and MMGi, NHT 2.5i, Revel Performa M22.

Subwoofer: Pioneer SW-8MK2.

Power conditioner: Audio Power Industries Power Wedge 116.

Interconnects, speaker cables and power cords: Shunyata Research Venom.

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