I’ve already reached out to PS Audio: they had me send in the unit for a firmware update, and I just received the unit back after that. There are reports on this forum (Roon and PS Audio Sprout100) and theirs (https://forum.psaudio.com/t/sprout-usb-audio-2-0-compliant/11486/) of the Sprout100 working properly with Linux after this update, so I believe the issue is with the Roon / ROCK software at this point.