The sound on Xubuntu with .19 on my little desktop system, connected via USB, is lovely, as it was with .17. However, I did once again when first starting Qobuz playback (upsampling to DSD512) get a frighteningly large POP! from my speakers. No pops, bangs, clicks when transitioning between tracks, or when unlocking exclusive access and then playing a new track/album. Only when starting Audirvana playback initially. Edit: It also happened on first playback after switching from convolution and upsampling to device maximum frequency (768kHz) to no convolution and upsampling to DSD512.
I have only noticed it with a local connection, not UPnP.