PS Audio PerfectWave DirectStream MK2 D/A processor

When Art Dudley reviewed the original PS Audio PerfectWave DirectStream D/A processor in Stereophile's September 2014 issue, he very much liked what he heard. "For those who've waited for a computer-friendly DAC that offers, with every type of music file, the best musicality of which DSD is capable, the PerfectWave DirectStream may be in a class by itself," he concluded. It was computer-friendly because, with an add-in card, you could connect it with USB or to an Ethernet cable and use it with, for example, Roon or JRiver.

DSD? The DirectStream's D/A conversion engine, designed by former Microsoft engineer Ted Smith, was unusual in that it synchronously upsampled all input data—regardless of format and native sample rate—to a 30-bit word length running at 28.224MHz followed by a digital-domain volume control. The data were then downsampled to 5.6448MHz, resampled to single-bit DSD128, and converted to analog with a low-pass filter.

Rather than using off-the-shelf chips, the DirectStream's digital processing was performed by a field-programmable gate array (FPGA). The performance could therefore be enhanced by reprogramming this FPGA and supplying users with firmware updates. Art installed the first firmware update while he was working on his review, and several firmware releases followed, culminating in the "Sunlight" version in 2021. Robert Deutsch, Jim Austin, and I reported on the effects of the upgrades up to 2017's "Huron" in follow-up reviews (footnote 1). I purchased one of the review samples in 2015 to use as my everyday DAC, fitting it the following year with the Bridge II network card in order to use it with Roon, and installing the penultimate "Windom" firmware in 2019.

Enter the MK2
PS Audio discontinued the original DirectStream DAC in 2022, introducing its replacement, the DirectStream MK2, priced at $7999, in January 2023. At 17" × 4" × 14", the MK2 is the same size as its predecessor, and with its gloss-black MDF top panel, it looks very similar. However, the original's rectangular, four-color touchscreen has been replaced by a smaller display with a Mute/Menu button to its left—a short push for Mute, a long-held push for the Menu—and a blue-illuminated five-button controller to its right. The left- and right-arrow buttons on this controller select the digital input; the up- and down-arrow buttons adjust the volume. After a long push on the Menu button, the controller buttons allow the processor's settings to be changed.

The MK2 has seven digital inputs: two AES3, optical and coaxial S/PDIF (one each), asynchronous USB Type B, and two I2S over HDMI. The last two can be used with PS Audio PerfectWave transports. There is no Ethernet port, but PS Audio will soon release its AirLens streamer/network bridge, which will connect to the MK2 over I2S. There is also a USB Type A port, which allows a memory stick to be inserted for firmware updates.

The USB Type B and I2S ports accept 16- and 24-bit PCM sampled at frequencies from 44.1kHz to 705.6kHz and DSD data from DSD64 to DSD256, natively or by DoP. The AES3 and S/PDIF inputs accept 16- and 24-bit PCM data with sample rates up to 192kHz and DSD64 DoP data; as usual, the TosLink input is limited to 24/96 data. The two AES inputs can be linked to accept DoP DSD128 data and PCM data sampled at up to 352.8kHz.

Every digital input is galvanically isolated to eliminate noise on shared grounds (footnote 2). (The galvanic isolation is bypassed by default but can be implemented for each input if needed in a specific system, using the Menu function.) There are now two FPGAs, though Smith says that only one is used with the current firmware. While the MK2 still converts the incoming data to DSD, it upsamples it to twice the original's 28.224MHz. The digital-domain volume control has been refined, with a new architecture with six levels of attenuation, which are automatically selected based on the requested volume level to preserve resolution. In contrast to the original DAC, there is no switchable analog output attenuator. However, the output level can be fixed with a Menu option at whatever level is selected by the volume control.

After the volume control, the 50-bit, high–sample-rate data are resampled to quad-rate DSD and converted to analog with a low-pass filter. The output stages comprise "high current, high speed analog amps" followed by galvanically isolated, balanced transformers. These transformers can handle higher currents with lower distortion than those used in the MK1 DirectStream.

I connected the DirectStream MK2 DAC to my Roon Nucleus+ server's USB port via an AudioQuest JitterBug FMJ filter. The PS Audio's balanced outputs initially fed the inputs of Parasound Halo JC 1+ monoblocks via 10' lengths of AudioQuest Wild Blue interconnects. However, the PS Audio's output dropped out at random intervals. It appeared that the weight of the cable's DC-bias battery was pulling the cable's custom female XLR plugs, which don't have the usual locking button, out of the DAC's jacks. The only other balanced cables I had to hand that were sufficiently long to reach the amplifiers were Ayre/Cardas Signatures, which I had been using several years ago. These interconnects use locking XLR connectors, and I had no further connection problems. I burned in the cables with a CD on repeat overnight before continuing my critical auditioning

The review sample had the v2.3.5 firmware package installed, but as I discuss in the Measurements sidebar, I rolled back the firmware to v2.3.3 then updated to the v2.3.6 package with the 198-Antero FPGA firmware when it became available for download (footnote 3). A long press on the Menu button and scrolling to the right brings up a display showing the firmware version and the unit's serial number. The DAC has sufficient storage for up to 10 firmware versions, making it easy to switch among them.

My original DirectStream DAC hadn't seen audio action for a while—I had been using MBL N31's CD player/DAC since I auditioned its Roon Ready update in 2020, followed by Benchmark's DAC3 B. I therefore spent a week refamiliarizing myself with the MK1's sound before starting my auditioning of the MK2, using the KEF LS50 minimonitors. To ensure a fair comparison with the new DAC, I used the MK1's USB connection.

The MK1 PS Audio DAC couldn't match the low-frequency drive and authority of the inexpensive Benchmark DAC that preceded it in the system. (Readers may wonder how I could perceive this with the small KEF LS50s, but I use Roon's parametric equalizer to add a 3dB boost below 75Hz with these speakers.) But while it doesn't have the almost unrivaled transparency to recorded detail of the Benchmark or the combination of transparency and effortlessly musical reproduction offered by the more expensive MBL when used with its Minimum-Phase reconstruction filter, the 8-year-old DirectStream's presentation was smooth, easy to listen to, and never got in the way of the music.

Footnote 1: All of our coverage of the original DirectStream processor can be found here.

Footnote 2: See Ted Smith's presentation on the design of the DirectStream MK2 at

Footnote 3: Thorough instructions on how to update both the user interface firmware and the FPGA firmware can be found in the manual, which can be downloaded from

PS Audio
4865 Sterling Drive
CO 80301

hollowman's picture

In one of the PS Audio YT videos, Paul M shows the lobby showcases at PS Audio HQ in Colorado. In them are all the products PSA has developed over their history.
For DACs, there have been several UltraLink models. Here's a Stereophile review from 1995:
It would be curious to re-review a fully-working classic DAC -- and compare/contrast w/the latest DAC.

John Atkinson's picture
hollowman wrote:
It would be curious to re-review a fully-working classic DAC -- and compare/contrast w/the latest DAC.

In 2019 Herb Reichert compared the original PS Audio DirectStream DAC with the 1989 PS Audio Digital Link. See

John Atkinson
Technical Editor, Stereophile

hollowman's picture

JA: thx, for the link to the Link!
And I did see that you also measured that old dac in 2019 with modern metrological instruments, like the SYS2722.

The Digital Link used the then-new Burr-Brown 18-Bit DAC chip, the PCM 61P, in a dual set.
In the Link, the entire d/a chip set seems to be:
2 x PCM61P - YM3434 - YM3623B

Image here:
Some possible issues with Herb Reichert's 2019 comparison might be the age/condition of those eletro caps (are they orig. in his re-review unit ?). Also, the lack of I2S direct input may have compromised sonics between the two units.
As a far as JA's note about Most Significant Bit (MSB) adjustment ... first thru third gen Philips dacs (up to Bitstream) dealt with that issue "expensively" via DEM (dynamic element matching) and external ceramic coupling caps (e.g., the tda1541, on the 3x2 bit active divider pins). Later multi-bit dac chips addressed the MSB issue internally (Philips Continuous Calibration) , as AD did with their AD1862, and trimmer pins, as does the PCM61P . Modern R2R discrete dacs, deal with this via dsp control.

Nota Bene:
Re-measuring (and re-reviewing) older, well-kept gear is a very good idea! It keeps the new-equip manufs in-check; and the 2nd-hand communities (AudioKarma, Audiogon), objectivists (Hydrogenaudio ) and DIY communities all interested and engaged in what mainstream hifi media are ... ahem ... "agenda-ing."


MhtLion's picture

Subjective listening and the musical enjoyment is another thing. But, how I interpret the provided measurement here of PS Audio PerfectWave DirectStream MK2 D/A is that this DAC is not worth its asking price. Personally, these measurement speakes that PS Audio does not have the industry leading engineering pedigree when it comes to a DAC.

I'm not saying this is a bad sound DAC. Not at all because I haven't heard it. But, in order for a company to say 'we know a thing or two about a DAC' it first need to produce a good measurement or at least very good at making elaborated BS claims why they product intentionally sucks at the measurement, which apparently some people buy. Have you tried a popular DACs under $900 with a $100k system? Schiit, Topping, SMSL - They are sounds good playing with systems 10X of their retail price. To say a DAC sounds good - doesn't mean much. I don't remember any bad sounding DAC above $500 in last a couple years. To get a merely sounding good DAC, you don't have to spend $8k. For $8k - it needs to be special. It needs to so good that once taken out of system you miss it, cannot stand without it.

Glotz's picture

But the various online audio communities tell everyone they do. Largely, because they don't have experience listening to the gear, and measurements 'tell' them they don't need to listen.

Yet, when everyone actually listens exhaustively to the SMSL and the Topping DACs compared to $10k plus units, they suffer in image size, depth of field perspective and focus.

Any DAC can be placed in a $100k system and will sound pretty great. It's the DAC at $10k and up that need to justify their position in those systems... and do. They prove it in the listening. There would not be a market for those expensive DACs if not.

By price and measurements, though excellent, you still dismiss the PW DAC.

For a DAC to be 'special', you haven't noted any parameters for such, other than price and measurements.

hollowman's picture

I’ve gone thru Ted Smith’s videos and posts about how DSD “is” the “analog” signal and all one really needs to do is LP filter. That’s a very simple interpretation; please correct me as needed!
I was going thru the HiFiEngine’s schematics and serv. manuals and ran across the Arcam Black Box “Delta” series of DACs.

And comparing to the master digital chip list on:

That dutchaudioclassics list has the wrong chipset for the Black Box 500 DAC. Going thru various Black Box schematics, Arcam did what I believe Ted suggests--way back in 1993!!! The TDA1307 is a rare and unique DF, made by Philips, and used various Philips / Marantz products --- including the very high end Marantz SACD unit from 2000.

The 1307 got little attention because the PMD100 chip with HDCD was the hot, attn-grabbing rock star in the mid/late 1990s. The TDA1307 interpolator converts I2S (PCM) to Bitstream (“DSD”). And then Arcam follows that with their own, custom “Bitstream digital to analog converter (DAC)” which may be what Ted had in mind. Not sure. The schematics for the Black Box 500 are readily avail at the usual places. Have a look!