PS Audio Stellar Gain Cell DAC

There's no shortage of choice for quality headphone amps. Whether your budget is $249 or $5,000, or somewhere in between, you should be able to find an amp that satisfies your requirements.

The same goes for D/A converters. The little Grace Design SDAC is killer at only $79 while high-end DACs routinely go for many thousands of dollars.

Preamps? Same story. As a more "traditional" hi-fi component, there's a seemingly endless supply of designs out there. A surprisingly large number of brands sport prices you might typically associate with a new luxury car. On the other end, Schiit's Saga does a bang-up job at $349.

Yes, there are more options than ever for building a system using separate components for each function. Yet things don't often go as well when using integrated devices.

Allow me to clarify: While the word "integrated" historically means preamp and amplifier in one chassis, I'm using it in the broader sense to describe devices with multiple functions built in. Those functions are D/A conversion, preamplification, and headphone amplification. It's pretty common these days for dedicated DACs to also have a pretty solid volume control implementation on board. I've also noticed many of the more traditional brands—Parasound, NAD, Krell, etc—are adding digital inputs on devices which they bill as "preamplifiers". The lines between these devices are becoming blurred, and it's not that hard to find both functions executed really well in one device.

Unfortunately, one thing that doesn't typically hold up so well is the integrated headphone amplifier. Manufacturers often throw in a headphone jack just to augment their feature list. If it appears on a more traditional integrated amplifier, historically there's a good chance the headphone output is based on a simple voltage divider drawing from the speaker amp section. These typically have massive output impedance—not ideal in the least. I'd call them "functional" at best. In many other cases the headphone out is built around an extremely simple opamp-based circuit even in devices where the rest of the design is quite advanced. These headphone outputs tend to range from "terrible" to "perhaps halfway decent." The latter I can work with, but wouldn't it be nice if the headphone stage was on par with the other functions on board?

PS Audio seems to agree. Their new Stellar Gain Cell DAC makes a legitimate claim towards three-in-one versatility, where each aspect seems fully realized. When no single part is better or worse than the others, it makes for a well balanced and compelling piece of gear—assuming you actually make use of all that functionality.

I've been playing around with the Gain Cell DAC—which is perhaps not the ideal name considering its versatile performance—for a few months now, and find myself very impressed. Let's dig in to see what makes this thing tick.

PSAudio_GainCellDAC_Photo_Rear

DESIGN
The Stellar Gain Cell DAC, or GCD for short, is a full size component. That already sets it apart from the Benchmarks and Myteks of the world who deal in half-width territory. The 17 inch width allows for impressive connectivity: on the digital side, we get dual coaxial, Toslink, DSD-capable USB, and I2S in HDMI form. Analog inputs include three sets of RCA plus a single balanced XLR. Outputs cover RCA, XLR, and the all-important front panel 1/4" headphone jack. That's a generous total of nine inputs and three outputs. I suspect very few listeners will have the need for more connectivity than what PS Audio offers here.

As the name implies, the Stellar DAC is centered around PS Audio's proprietary Gain Cell technology. This is a clever method of analog domain volume control whereby a spin of the knob results in changing the amount of gain applied by the circuit. This ensures peak performance at every volume level, for both the headphone stage and the line out. As a fully balanced design, the Stellar DAC uses a separate Gain Cell for each channel.

PSAudio_GainCellDAC_Photo_GainCell

Contrast that with the vast majority of competing designs which involve some form of attenuation. The usual suspects are potentiometers and digital volume solutions, both of which often involve some type of compromise. This is particularly true with headphone listening where levels might be set lower than they would be on a speaker-based setup (or at least that's how it ends up for me). Standard potentiometers often have trouble with channel-matching at low levels, to the point where sensitive headphones (especially IEMs) can become unusable.

Digital volume implementations tend to sacrifice resolution when the volume drops too low, resulting in flat, uninspiring performance. Exceptions to these examples can no doubt be found, and there are other worthy choices out there (stepped attenuators, for example), but the bottom line is this: PS Audio's Gain Cell implementation is right up there with the best volume solutions you'll encounter.

PSAudio_GainCellDAC_Photo_Chips

The GCD routes incoming digital signals through PS Audio's proprietary "Digital Lens" technology. This solution is a trickle-down byproduct of the flagship DirectStream DAC, which goes for $5,999. While that acclaimed design handles everything (including the actual D/A conversion itself) through custom-coded FPGA, the far more affordable Stellar DAC has to settle for off-the-shelf decoding from an ESS solution. The Lattice FPGA of the Digital Lens analyzes, reclocks, and "waveshapes" incoming signals, handing off a cleaner, lower jitter signal to an ES9010K2M Sabre chip for D/A conversion. This is not a top of the line chip in the Sabre series, but PS Audio says they tried a bunch and this one had the most natural sound in their implementation. That's an interesting tidbit which stands in contrast to the usual spec-wars we often encounter in digital audio.

Speaking of "natural"—aside from the gentle manipulation inherent in the Digital Lens, the GCD design places a high value on maintaining signal integrity. This is shown by the use of "native mode" rather than any form of sample rate conversion. It also shows up in the passively-filtered output from the DAC chip itself, which is said to reduce transient distortion. Fed by the Gain Cell volume control system, and run through a directly-coupled output stage, the idea is to put less "stuff" between the listener and the music. Or, to put it another way—just enough to do what needs to be done, but no more.

The headphone stage comes directly off the Gain Cells. The output is a hybrid design with opamps driving discrete transistors, direct coupled and biased heavily into Class A. The result is a healthy 1.5W into 32 ohm loads or 300mW at 300 ohms, with an output impedance between 3 and 4 ohms. This means the majority of full-size headphones will be well fed, though care is required with IEM matching. I tried favorites from 64 Audio, Empire Ears, and Noble, and found pleasing results on a case by case basis. I'd say the impedance is not the main culprit so much as the slight background hiss, which somewhat overpowers the most sensitive models. But I'm very picky when it comes to hiss, and tend to listen at lower levels than most folks, thus further exacerbating the problem. Many listeners and IEMs will do just fine here, and having perfect channel balance at all volume levels is much appreciated.

Externally, the GCD is relatively simple but rather fetching in my opinion. Build quality is generally impressive, though I was initially a bit put off by the somewhat rough textured finish of the enclosure. I guess I was getting used to the smoother finish as found in Schiit Audio gear—which bears a vague aesthetic similarity to the Stellar products. Eventually I came to realize the choice of texture isn't better or worse...just different. Like Schiit, PS Audio designs and manufactures all their equipment in the USA—Boulder Colorado to be exact. All Stellar products are available in silver or black, and as usual I prefer the former, though I admit a stealth black version has its own appeal depending on the system.

Information is displayed via OLED panel which I find far more useful than the typical LCD or, worse yet, the banks of indicator lights favored by many competitors. There are quite a few options to sort through—user selectable digital filters, renaming of inputs, channel balance, display brightness and timeout, and so on. PS Audio makes all this happen with just a single button and knob combo which I find highly intuitive to use. Other designers should really take note of this solution. On a side note, I really dig the PS Audio logo which doubles as a sort of "hidden" on/off button, keeping the front panel design clean.

PSAudio_GainCellDAC_Photo_Volume

I can't speak highly enough about the feel of the volume knob. It's one of those things that sounds small, but in reality is pretty important considering it's the main point of interaction with the device. Hard to explain, but I'd rank the feel of it up there with the very best I've experienced. It's easy to get a little detail like this wrong—most people won't complain as long as the thing works well enough—but getting the weight and feel just right takes a lot of work. I'm curious how many iterations it took before PS Audio arrived at this final design; it really is something to be proud of, as inconsequential as that may sound.

Now, on to the listening.

COMPANY INFO
PS Audio
4826 Sterling Drive
Boulder, CO 80301
(720) 406-8946
ARTICLE CONTENTS

COMMENTS
tony's picture

...that you like PS Audio?

I've worked with these guys since the 1980s, hmm, I guess that I like em', they're good guys. I even follow Paul's New YouTube Channel where he gives rather bland answers to folk's questions. Typical of Paul's vagueness but I still like him and like working with him. I'm even considering owing a PS Audio DAC ( now that I've lost interest in that Shit Company that I've been loyal to since 2011 ).

I rather like the Polish Mytek stuff, too.

I'll be driving the big Genelec "1" series with matching SubWoofers.

MQA might be the deciding element.

Paul says that DACs pretty much sound identical, it's their Power Supply and audio output circuit that makes the difference in their audible performance. I presume that the IRS System in PS Audio's sound room is their tool for evaluation and the basis of their confidence, do you think so too?

PS Audio was the very first Audio Company I was a dealer for ( back in 1982 ) when we were setting up B&K imports in Michigan, Paul & Stan were a wonderful hoot for me and my partner George ( who went on to become the CEO of 3M Corp. ) George retired and has a early PS Audio Integrated Amp running his early Thiel CS3s. Those were the good ole days.

Tony in Michigan

ps. Betcha a nickel that Paul reads this.

John Grandberg's picture

I can say I like this particular PS Audio product quite a bit. Like any other brand, I'll reserve judgement on their other stuff until I hear it, and judge each model separately regardless. Everyone - Schiit, Sennheiser, Audeze, Sony, Genelec, etc - has hits and misses.

I do believe PS Audio still uses their IRS setup for listening evaluations. Apparently the Stellar Gain Cell DAC was almost 2 years in the making, with lots of listening involved.

Anyway, thanks for the insight into your PS Audio history. Good stuff!

badboygolf16v's picture

It's a shame that there are no measurements to accompany the review. It's almost like it's not an Innerfidelity review!

John Grandberg's picture

Tyll made some progress on his amp measurement routines a while back, but that got sidetracked and is still not done. Now he's going full steam ahead with a revamp of the entire measurement system for headphones.... so I really don't know if or when the amp measurement process will be finalized.

If that day ever comes, I'd be very excited to start building a collection of measurements for each amp review. It will be illuminating to see trends as to what contributes to the slight differences in sound people tend to hear between amps. Likewise, I'd love to nail down the shortcomings in technical performance which contribute to audible flaws when driving certain headphones.

geniekid's picture

Thanks for the info. Glad to see some DAC/Amp reviews.

Mike in Tampa's picture

Hi John, obviously the Cayin stack has a lot more flexibility, but how would they compare with the Stellar purely based on sound quality?

John Grandberg's picture

...the Cayin DAC and headphone amp duo has more options for tweaking the sound, and its amp section is more powerful (and balanced too). But the Stellar is significantly better in the role of preamp, which is one area the Cayin doesn't really shine. So it depends on whether or not you have a need for that.

If I had to rank them on the other two aspects, I'd say the Stellar is better at the DAC portion, while the Cayin does better driving headphones. But again, that's really generalized. I honestly don't think you can go wrong either way if the preamp section doesn't matter to you.

Mike in Tampa's picture

Thanks for the reply John. Another plus for the Cayin system I suppose is the ability to add the matching DAP (which you also seem to really like) to the stack. Happy Thanksgiving!

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