Do USB DDC interfaces make a difference with the PSA DS MK2 DAC?

There have been a lot of threads here over the years about using USB Direct Digital Converters with the DS MK1. What are latest experiences with the MK2?

I have two USB devices immediately upstream from my PSA DS MK2 DAC:

  • A Mac Mini i5 powered by a TeraDak LPS and running BACCH4Mac to output via USB
  • A mini-PC powered by an LPS and running HQPlayer OS NAA in RAM (no drive installed) to output via USB

I’ve been using a Topping HS02 to switch between USB sources. I did not expect to get any SQ improvement from it from its isolation properties. These are apparent when putting it between a laptop and a small USB-powered DAC. But a D10S is not a MK2.

For the MK2, I just use the HS02 to switch between USB sources. The physical switch is in between the input cables. And, although my fingers are not so thick, the USB-C side is getting wobbly. See picture. And, unfortunately, sometimes there are popping sounds during playback that only go away once I switch to a direct cable run from the source device to the DAC, not using the HS02. Later I can put it back and have no popping…

One idea is to get a Holo Red instead. This could work as a DDC from the Mac Mini. And I could stream to it from HQPlayer after a reboot. No need for the mini-PC anymore. iFi Zen Stream should do for this too.

Another idea is to get two Matrix X-SPDIF3’s. The MK2 conveniently has two I2S inputs. But not two USB inputs. Two Audio-GD DI-24’s would do as well. But it is maybe a bigger box than I want. Ditto the Denafrips Iris.

And given asynchronous USB on the MK2, I am less keen on getting a USB DDC with reclocking chips.

Ah heck, I could just go back to USB cable from the Mac Mini to the MK2 and use my SMSL PO100 Pro to get I2S from the mini-PC to the MK2. Though I always have to be careful to check that the left-right channels do not get swapped with DSD.

And so I go in circles…

What have folks out there tested DDC-wise with the MK2? Views?

With my current Bacch4Mac setup I am using a USB cable between my Mini and my Tambaqui. The Tambaqui has many inputs including I2S and I have a Matrix sitting on the shelf that I have zero interest in trying out. I just don’t care. When my upgrade for my adio is done and it returns I won’t have any USB anything in my system.

People here have commented that they used DDCs with their MK2 DACs and if there was an improvement over straight in USB it was negligible. I just can’t imagine multiple USB sources.
I have unbalanced cables between my phono preamp and BabyFace Pro. The Grimm MU1 only offers SPDIF and AES outputs that are useful. Right now I am listening to the MU1 as a Roon Server only and the Mini as a Roon Endpoint. There is no reason for head scratching with this choice, it sounds great.

For me the BACCH toys just end my desire to mess around with all the possibilities of this and that. And now with ORC Room Correction I feel it’s a “Stick a fork in it, it’s done” situation. Hopefully you will have a chance to experience it yourself real soon now.

“Comparison is the thief of Joy” Theodore Roosevelt

1 Like

That is a gem we could all use

1 Like

I thought that @tedsmith already provides an ultra clean clock for all the digital inputs for both my MK1 & everyone else’s MK2. That these reclocking devices aren’t necessary since the jitter cleanup/reduction is already taken care of inside our DAC’s.

1 Like

It’s not that simple - the issue usually isn’t clock jitter but instead ground loop issues and/or radiation issues on the interconnects interacting with the rest of the system. In many systems even with no DAC in the system a device added to the system can cause better sound (or worse sound) (when other parts or the system are the source) just by adding or deleting a ground loop, adding a more synergistic cable for part of the new system, etc. There are certainly reclockers that made systems with the Mk I sound worse and those that made it sound better. The Mk I was already very good at rejecting jitter, but not as good at dealing with ground loop noise, etc.

On the other hand some have discovered that the Mk II’s USB is good enough that some systems are better off without USB to whatever converters before the Mk II. Others still like something there.


I thought the MK2 already had an optically isolated USB input?

Yes indeed. But note that I said that adding a DCC to a system even without the DAC present can still change the sound of the system. We’re talking about effects that are very subtle (in many cases.) The changes that we are hearing almost never have any correlation with the intended function of the boxes in question. It’s much more often how the boxes change RFI, ground loops, etc. in the system as a whole that matters. Adding a box will almost always cause another one or two groundloops because of the safety ground, etc. on the new box. Sometimes this makes things worse in a system, but it can also make things better.


Understood. Thanks for confirming. I just wanted to double check with you on the optical isolation of the MK2’s USB input - which I would assume to have the most dominant impact on overall system performance.

Ah. I missed your point. Anyway, being pedantic here: I could have been a little clearer - it’s not optical isolation but instead GMR. Unfortunately, more expensive than optical isolation, but it can handle a higher clock rate.

The big advantage over capacitor or transformer isolation is that it doesn’t use On-Off Keying. To get a DC signal across a cap or transformer digital isolators have little oscillators which they turn on to indicate a one and off to indicate zero. This high frequency interference can be worse than the original problem. GMR doesn’t have that problem and is magnetically and electrically quiet.


I am one of those “happy with USB on the MK2” people. It is just that I have two USB sources. The Mac Mini running BACCH4Mac receives and sends 24-96 PCM. But I also enjoy my NativeDSD 128 and 256 files and also enjoy helping to check HDTT DSD256 files. Tried a couple ways to get DSD through the Mac Mini as DoP today without messing up the BACCH4Mac settings too much. This would allow having just one USB source to the MK2. Did not quite succeed though, at least not in a way that I can flip back and forth. Thinking next to put Foobar for Windows into Wine on the Mac Mini, as the SACD components for Foobar cannot be loaded in Foobar for Mac. Would let me avoid adding devices like extra DDCs or buying other software.

JRiver MC doesn’t cost that much and I think it will do what you want, i.e. for example it provides a ASIO device interface that it can use as a source…

Also, if you are adventurous, perhaps a USB switch would fit the bill. The HD3SS6126EVM is an eval board for a TI part. As such it doesn’t have an enclosure and the documentation is directed at someone who is evaluating the TI switcher part, but you can use jumpers on the board to select which host is connected to the device side. I’m not sure if this would work for you or not.
HD3SS6126EVM Texas Instruments | Development Boards, Kits, Programmers | DigiKey
Tho I think some of the cheaper, similar USB 2.0 eval boards might work for you I couldn’t be sure with only a read of their eval board documentation and they would require soldering to put the correct connectors on.


Thanks Ted! The evaluation board approach does not look beyond me.

BTW, any clues as to why my MK2 does not show under its own name in MacOS land? I have been advised that I could get DoP passthru to work if I were not to send to the MK2 as the “default audio output device”. On my Mac Mini, it is the “USB primary play interface” that I am selecting. Sure sounds like the same thing to me though. Via Linux machines, the MK2 shows properly as a “PS Audio”.

No, I’m not familiar with the non-data part of USB or much about Mac land at all :slight_smile:


Edgar does not believe in DSD. I do not believe any BACCH gear will be able to use it.

My problem is solved, oddly. Since I have an old Intel-based Mac Mini, I just booted it into Windows and all the usual ways I can play DSD from a Windows machine using the PS Audio ASIO USB driver are working. It is not what I normally will do. But it is good for demonstrations, as well as to help folks who are DSD based to do some testing for them. For BACCH, I just flip back into Mac OS. My server downscales from DSD256 to PCM 24-96 accordingly. No need to swap settings back and forth manually within one environment. Just boot one way or the other.

Of course, this is not the headline question here. Hopefully we will see during the coming week if any folks speak up who tried USB DDCs with their MK2 DACs and found the DDCs to bring improvements.

As Ted comments, lots of cables can bring interesting effects. My stereo system sits within a DSD surround system, which sits within a 9.2.6 ATMOS surround system. So I have LOTS of cables and lots of ground loop suppression, including in the satellite feed. Getting rid of all RCA cables and having only XLR was key. But keeping USB cables is working out so far!

1 Like

I use a Matrix X-SPDIF2 to get my M1 Mac Mini with I2S into my Mk2. This frees up the one USB input on the Mk2 for my Innuos Zenith Mk3, since I only really have one good digital cable. I never really considered my Mac to be the best source, so I didn’t do any super critical listening, but I can’t say I noticed very much improvement with the Matrix in the system—things still sounded digital to me. Adding DC power to the DDC didn’t do anything audible for me, although keep in mind that both USB and HDMI cables on this route are under $250 in value.

Adding the DC conversion to the Mac definitely went a little bit further towards taking away some of the digital sheen, but nothing night and day. I haven’t mentioned this anywhere else, but I ended up winning a pair of Jitterbugs from that Stereophile raffle and that made a huge difference on the Mac—way more than the sum of everything else. It doesn’t just remove a bunch of sheen, but noticeably expands the soundstage. I’m reluctant to tell anyone else to try it on their Mac because it’s a bit perplexing to me and I have a dim view of cheap little dongles like that; it’s certainly not something I would’ve purchased myself. I’m not even sure it improves the sound because of what it was designed to do, but I definitely think what Ted says is spot on because I sure don’t know why it seems to work. I tried it on a couple different sources to make sure I wasn’t going crazy, but it didn’t really have an effect on anything else. Maybe it says more about how the USB on the Mac is.

I should also clarify that these impressions are based on traditional playback; I haven’t gotten on the BACCH4MAC train yet. Reading about Al saying it ends the desire for tweaks, I don’t think I can hold out for very long, but I seem to be fighting a visceral resistance to going down a path that might put an end to compulsive tweaking. What else could an audiophile possibly find to do with his time?

1 Like

Listen to live music!


Music? That’s for the unfortunate non-afflicted masses. There’s definitely some Pavlovian self-preservation going on here.

1 Like

Ha! Ha!


I appreciate your comments! I have a Jitterbug in a drawer somewhere. I will have to try it.

I had two reasons for buying the Bacch4Mac setup. One, I needed to send my BACCH-SP adio in for an upgrade. I didn’t want to be without Bacch for an extended period. Secondly, I wanted to experience what the Bacch4Mac offers.

I bought and received an upgrade power supply for the Mac Mini and a monster of an external power supply to power it. I do not plan to install either until my precious adio returns. Personally I am horrified that all my sound is routed through an Apple Computer. I should have been the very last person on Earth to choose to do this. But damn, I am fine with the results. I can put a record on and by hitting one button take the entire Bacch4Mac setup out of the equation. I sometimes do this for upwards of 8 to 15 seconds at a time. I am not bragging.