UPDATED… Sorry I have updated a few times, as I observe issues.
OK, So I took the time to install Ubuntu Server 21.04 on a Series 4 i5 laptop.
uname -r = 5.11.0-36-generic
I then installed Roon Server.
All observations are with the Motu Mk5 lite connected to the Roon server via USB:
(Please bear in mind with the Motu directly connected to my RPI4, everything works perfectly)
Test 1: Stereo
When I set the device as 2.0, and downmix, Stereo works, but I get noise on unused channels.
I did experience crackle using my PC’s USB 3 port. Using a USB 2 port everything is fine (Cable?)
Easy enough to mute unused channels down in Cue Mix.
Next I set the Motu as a 7.1 device, channel mapping, procedural mix.
Stereo works, and it seems I get no noise on unused channels, no crackles etc using USB 2.0 port.
USB 3.0 port I have low level crackle (Could be the laptop or cable).
Test 2: Multi channel
I set a procedural mix, set the device to 7.1, channel mapping.
I get 8 channels of audio, and random noise appearing on channels 9-10 as observed on other threads. USB 3.0 I get low level crackles, similar to an old vinyl record.
USB 2.0 port is fine. I wonder if I need a more recent PC, or a new USB cable.
I’m using the OEM Motu one…
This is very odd, as the RPI4 running Ubuntu is perfect, on USB 3, or 2 ports.
I hope this helps everyone.