It is totally random. Sometimes the noise...distortion...dropout, I don't really know how to describe...occurs with the very first sound played, sometimes it happens after a few minutes. The DAW doesn't show any xruns. Strangely enuogh I just realized that I am not able to change the buffer size. I use Ardour, where you can set the buffer size at startup. It is set to 1024 samples. I can change that, but it seems to be completely ignored.

After a long time it seems to work now, but still not 100% reliable.

First thing, there was a headphone amp involved, which digital input seems to have problems with syncing via SPDIF. I tried 2 different ones and both had the same problem. Never encountered this with the HDSP before. Funny thing is, that I get distortion even on the internal headphone amp if the external one is connected.

The other thing was pipewire (my I say, as always? ).
Though I have set Ardour to use ALSA, it seems pipewire doesn't let the Digiface go...I had to disable the Digiface in the KDE sound settings completely, then the Ardour settings finally applied. At least the crackling is gone, but from time to time there is still a kind of distortion and some weird phasing. This is much less frequent than before, but not 100% gone.
Another funny thing is that xruns increase if I set the Digiface to higher buffersizes than 1024 Samples. It seems that nothing else works, it has to be exactly 1024. With 512 load gets too high, with 2048 it stutters massively.

Depends. The particular project I was testing with is quiet plugin-heavy. I have about 30 mono audio tracks and 18 or so groups and auxes in stereo. There also are a lot of MIDI tracks and unused audio tracks, but those are inactive and not visible. I use quiet a lot compressors, eqs and a few multiband compressors, mostly LSP stuff. I usually don't care about latency, because I do not do recording in this setup. The hardware is nothing fancy, just an old Core i5, 16 GB RAM and a TB M.2 SSD.

What is special is the old HDSP 9652 PCI on a PCI - PCIe bridge. I had to cut holes in the case to be able to fit it in . But it works very well and I am a bit dissapointed that the "clean" solution with the Digiface doesn't work so well.

I am still experimenting a bit. Now I did the following:
I set the HDSP to active so pipewire can use it.
The Digiface is not visible for pw.
I fed the ADAT output 4 from the digiface to input 1 of the HDSP.
HDSPConf shows stable sync on ADAT 1.
When I play Audio through the Digiface (again Ardour), it woks for some time, then crackles and ditortion come, sometimes just short, sometimes longer. HDSPConf shows stable sync all the time. Sometimes if I change the outputs in Ardour the crackle goes away, but not always.

As far as I can tell the same behaviour happens if I connect the Digiface to another computer (also with Manjaro though).

After nearly fucking up my system (as expected ) by removing pipewire the conclusion for me is:

1. As far as I can tell it works as long I use only the internal headphone amp.
2. If I connect anything to the digital output the crackling, distortion an phasing on that connection, no matter what I connect. This happens randomly, I wasn't able to find anything to trigger that. This also happens if I only play e.g. a youtube video or so, it's not related to Ardour.

I checked the other devices with the HDSP, too, so I am sure they work and it's not a cable issue. I even set up another machine with Ubuntu Studio, but the problems persisted.
I am quiet sure that it's some kind of sync problem, but I can't find out what causes it. I even changed cables and ports several times.

What I could not check is if works with Windows. I do not have a Windows machine atm.

With alsamixer you can monitor the current input sync, input format, device rate and system rate settings and adjust the sync source and output format settings. Select your Digiface USB with F6 and then the output format and sync source settings are at the end, just before the System Rate setting.

Where do you configure sync settings? Possibly that's not set up correctly.

Depending on DAW and plugins architecture the buffer get overstressed more and more until the system breaks down and you receive crickle crackle, try Reaper instead of Ardour.

Can the mixer application configure sync settings? Maybe it can, must admit I'm not familiar with it. Which device is master? Make sure one syncs to the other, they can't both run on internal clock.

The current setup is Digiface as master, connected are 3 Behringer ADA-8000 as slaves. But it doesn't matter if there is anything connected, the distortion always happens sooner or later. I tried the exact same setup with Windows and ther were no problems. The only thing that was different was the USB cable, which I swapped, too.
Yes, alsamixer can change the sync settings.

I believe the kernel support/driver is faulty.

Thank you, I just tried liquorix, but sadly that didn't change anything. I think I give up and stick with my HDSP for now. Maybe I'll try some time in the future.

I've been trying something similar for the past week and just gave up.

Essentially i just switched my all-day setup to CachyOS and wanted to use my Digiface USB for all Desktop audio.

But i also encounter weird audio issues that happen randomly and require restarting the audio stack.
I would describe the audio as becoming metallic/robotic sounding like there is a sample-rate mismatch happening.

Once that starts, that "effect goes in and out but won't go away until you restart the stack (sometimes multiple times are required as well).

I've tried a variety of things to no avail:

• Enabled RT, set RTPrio / nice.levels and changed memlock to unlimited

• clock sample-rate, allowed rates and force rate to  48000 (including locking)

• tried various quantum variations with and without forcing them

• checked pw-top for any possible issues, but i don‘t have any errors at all v

• dmseg hasn‘t shown anything out of the ordinary as well

• check cpu load, but my system is usually bored and uses around 5 - 10% overall while testing this.

• disabled usb autosuspend just in case

At this point i'm out of ideas and just decided to not use it on Linux and just keep dual booting into Windows if i need to do creative work.

As they say - a problem shared is a problem halved.

Oh interesting! Thank you for sharing.

Yeah my device shares the same bus with one other device (Corsair H150i Platinum AIO cooler).
I‘ll definitely give your suggestion and tool a try to see if that helps and will report back.

I just discovered that the issue seems to dissapear if one sets the sampling rate higher than 48 kHz. I made 2 identical projects in Ardour, one with 48 kHz and one with 96 kHz. Almost instantly crackling and distortion starts with 48 kHz, none at all at 96 kHz so far.

The Digiface is too proud to work with high latency

Hi,
I confirm RMEDigiface USB works great, I performed 3 days on a 32 channels acousmonium and some ADAT inputs with no xrun.

BUT: doe's anyone know hot to set the Digiface in WordClock slave mode? I can set the mixer as slave, but when connected to Dante it is a really bad idea...

that is the point, there isn't, it use ADAT

actually Dante is the master of everything. I don't really get what you mean by "Fireface USB settings of the Digiface"

Anyway, the answer is in Alsamixer, there is a Sync Source option where you can choose any ADAT input or Internal.

Thank you!

Amazing! Been running this now for a week now, without issues thanks to your post.

Lowest i’ve tried to set quantum / buffer size was 128 and didn’t even consider going lower.
After setting it to 64 - the issue has never come back!