Nucleus and Directstream Jr. USB loses connection

I’m using Nucleus connected to Directstream Jr. via USB. Nucleus and Roon are up to date and Directstream is using latest (Redcloud) driver.

Everything works fine for a while, then at some point the connection is lost, with a sound like lifting the needle from a turntable. Roon seems to keep playing, but no sound. If I reboot the DAC, everything is good again for a while. If I try to reboot Roon rather than the DAC I get strange behavior, like the “play” graph at the bottom zooms back and forth, or the program quickly zooms through my entire queue (without playing).

Everything was OK when I was connected directly to the DAC USB from my computer (as the Roon Core). Also, Nucleus out to the Directstream Jr. Bridge seems OK (though I prefer the USB sound, so want to fix this). So the problem seems to be with Nucleus USB. I did add the Nucleus and Redcloud at the same time, so it’s possible that it is the Redcloud driver, but seem unlikely as no one has reported this behavior anywhere that I can find.

Also, just FYI, I’m using internal storage on the Nucleus, and have tried “resync delay” up to the maximum delay, but the problem persists.

Please let me know if you need any further info, and many thanks for the help!


I imagine you are experiencing the fun bug in the XMOS usb chipset when changing bit depths it causes the DAC to hang on Linux (Nucleus is Linux based). For testing this theory you can try one of two ways. Either in the dacs device setup limit the bit depth to 16bit should be in the advanced section or you can use the DSP engine to upsample all to a given sample rate and bit depth this at least allows you to get the highest resolution, you can choose DSD or PCM x 2 If you get no issues using either of these then it’s the XMOS chipset that is likely problem. Roon have addressed this issue with manufacturers as it’s not just a Roon problem and may have a fix before long.

Here’s my ticket on it.

Hello @Michael_Fulwiler,

Thanks for contacting us regarding this issue. As @CrystalGipsy mentioned it is possible that you are seeing the XMOS chipset issue in your setup and if you are able to confirm this it would be a good step.

To perform the test he suggested here is a visual guide:

Test #1:
Open Roon Settings -> Audio -> Cogwheel Icon next to DirectStream Zone -> Device Setup -> Scroll down to Advanced -> Set Max Bits Per Sample (PCM) to 16. This setting should look like this:

Test #2:
Open Roon Settings -> Audio -> Cogwheel Icon next to DirectStream Zone -> DSP Engine -> Sample Rate Conversion -> Enable-> Also Sample Rate Conversion to Max PCM Rate. These settings should look like this:

Please let me know if the same issue occurs with either of these tests and I would also make sure that the Signal Path is showing a consistent bit-rate between tracks (as in the bit-depth of 16 or 32 does not change.


Thank you both Simon and Noris! Will give these tests a go. There is at least some comfort in that it is a known issue and is being addressed.


I did a fair amount of testing on this. I found two files where the transition between the them reliably crashes the DAC (44kHz, 16bit FLAC to 44kHz, 24bit AAC). With the DSP engine off, it crashes about every 2nd time I try the transition.

Both options offered (forcing to 16 bit or using Max PCM rate) seem to mitigate the problem - no crashes so far.

I also tried what Brian mentioned earlier in the thread - using two gain modules (procedural EQ) that cancel each other out. This also seems to mitigate the problem, with no audible changes. Max PCM seems to smooth things over too much, and forcing to 16 bit doesn’t seem like a desirable long-term choice - though a good test.

I will use the Procedural EQ option for now, and will chime in if this fails at some point. It seems that PS Audio is releasing an update any day now (Snowmass) for the DirectStream Jr., so likely won’t have incorporated this fix yet - probably have to wait another year . . .


Hello @Michael_Fulwiler,

Thank you for running those tests. It appears that the PS Audio engineering department is aware:

Snowmass seems to be affected too unfortunately, but I will share any new developments with you as they arrive. For now if you don’t have this issue using Procedural EQ I would keep using that and if you experience any other issues in the meantime please keep me posted.