Thinking of a new USB DAC

I am currently using an R-PI 3B+ with an ropieee image for now with an Audio quest dragonfly red plugged in which of course works well, however I want something I can permanently leave plugged in as I use the dragonfly in the car and elsewhere.

DACs I have been considering:

Pro-ject pre-box s2 digital, but I still have concerns over its support and current software state, but at least it supports MQA.
RME ADI-2 DAC - loads of concerns here - while it has some great features inside and is of knows great audio quality (I use other RME in my studio for audio work) at a fixed sample rate, it seems when implementing USB feature they never gave a moments thought to the reality of HiFi use of a DAC (lack of HID volume control, lack of sample rate switching support as far as I can tell and apparently the barest minimum implementation of ‘class-compliant’ USB audio that people some to be having issues with).

Beyond these two, there is nothing much that grabs me. Of considerable concern is that any DAC that cannot be told to switch to optimal sample rate and does not support device volume will be compromised when having to use roon’s equivalent capabilities which Im sure are good, just as roon say themselves - not done in the ideal place.

The dragonfly I already have just works with zero hassle and works very well. Because it is full featured and properly implemented, then while it may not be as good a DAC in ideal circumstances as the others above, a lot of the time it seems to actually result in better sound simply because it integrates far better and thus does get compromised.

Are there any other sub 1K USB DACs worth looking at that are full featured with Roon and would work with a raspberry PI 3B+? One of the things I liked about the RME DAC was dual outputs (balanced and rca) as Ideally I would like to dual connect it, but this isn’t a big deal. Something that just works fully and properly would be a good start and doesn’t have a compromised USB control :slight_smile:

FWIW, I purchased a Pro-ject Pre Box S2 Digital to use specifically with Roon. I’ve had it about a week now, and with the 2.12 firmware (which it came with, so current shipping stock has the most current firmware pre-installed) it has been rock solid and I’ve been very impressed with the sound quality. (FWIW, I have it connected to my iMac Pro in my home office, and use Gorilla Ears GX-8 custom in-ear monitors with it.
I am using it strictly as a headphone DAC/AMP; I am not using the line outs.)

Disclaimer: I have no MQA tracks, nor do I subscribe to Tidal, so I’ve never tried MQA through it, which is where I believe the remaining gotchas are from the forum reading I did before buying it. I don’t particularly care about MQA, so this wasn’t a real concern for me.

Is there a reason you are not considering a HAT? The IQAudio stuff is impressive, I have a few of those running with DietPi and Ropieee images.

Because the R-PI is what I am using now - it might not be what I am using in 6 months :slight_smile:

Also as I am using a touchscreen pi, then I cant fit anything else in there without getting another case and I’m not liking the various options I have found and lack the tooling to cheaply construct my own case.

Yes, I expect it would be rock solid on a Mac :slight_smile:

I don’t need a headphone amp - my integrated amp (Yamaha A-S2100) has a really good one for the rare occasion I use headphones. You not getting any sample rate and/or MQA mode change change pops?

No pops between sample rate changes or format changes (meaning between PCM and DSD audio files). I have no MQA files, so can’t test if switching to/from MQA results in pops. Again, MQA is not in my requirements or care list… :slight_smile:

I use this as the headphone amp in my home office. While I also have a Sonos Playbar in the home office for the office TV, there is a quite lot of ambient noise from system fans and the air conditioner. So using headphones has its advantages when you want to just block everything out.

@Adam_Goodfellow, yup! Agree on all counts. I have looked at some options from Thingiverse and Instructables, but nothing I want to use on my primary stereo. They may be OK for my office :-))

If you find any tooling or pointers I’d appreciate a headsup. Happy to CNC or build stuff if would look great and work well.


I’m using the ProJect Pre Box S2 (terrible name) and really like it. I would suggest that you get to to do the first unfold of MQA and just let the DAC do the final processing.

Sounds marvelous like this, with our without MQA.

I will say check the forums as using the wrong filter messes up the MQA. The filters don’t make much difference anyway

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To be fair - I am not overly fussed about MQA - yes there is a positive difference on the dragonfly but not much to write home about, OTOH, if something is available and its an improvement, I don’t want some botched/minimal implementation to get in the way of it - that’s the reason the RME ADI-2 DAC is out of the running, and the S2 while very interesting what I have read does leave me with some concerns at least until its creator (john Westlake?) does his own update for it.

I assume the S2 DOES manage to switch sample rates to whatever the optimum is under roon bridge control?

I have had zero issues with it switching between bitrates. Also zero issues switching between PCM and DSD. While I did test sending it 768k PCM and DSD256 (no native DSD drivers for OSX, so no DSD512 available) to make sure it worked, I don’t actually do crazy upsampling in my normal playback. I just have it playing whatever the native bitrate of the particular recording is.

You mentioned USB volume control. While it does support that, it doesn’t update the display when used. Personally, this was not an issue for me, as it’s on my desk next to my Mac within arms reach. I have it set to fixed volume in Roon, and use the volume knob directly on the unit when needed. But even that is pretty rare, since I enable volume leveling in Roon (volume leveling is mandatory when Roon is randoming in radio mode and pulling tracks from all over the place).

Hi Adam,
Where did you hear about the sample rate switching issues with the RME ADI-2? Just curious because I am considering auditioning one if possible.

A bunch of people have been complaining about (lack of) sample rate switching with standard OS drivers. At the time the Linux drivers appears to be a bit ‘beta’ and as for any hope of their support taking use with a Raspberry Pi seriously in case of any issues? :wink:

In the end, I just felt that anything that may hinder completely hands-off operation was a no-go for me personally as my AV is very highly integrated with home automation and Roon.
In the end I went with a pro-ject pre-box s2 digital.

I do like RME devices having used them in my own and other studios over the years, but I do not get the feeling they really ‘get’ or are keen to embrace modern home automation integrated AV/HiFi systems and thus do not see missing features that hinder such an issue. TBH I was also surprised that they decided not to do OSX drivers for it either as I had planned on dual use as a hifi interface and as a mastering interface, but OSX core audio vanilla drivers are not exactly low latency :slight_smile:

For pure audio quality, I would buy one blind such is the faith I have in their ability to delivery great audio quality. Over the years however I have never known them to very receptive to feedback.

But don’t let my reasons to going elsewhere put you off.

OK thanks. An update is available that may have fixed some of the RME issues: