Hi @Helmut_Lehr – sorry for the confusion here, but to be clear Roon does not support UPnP. We can stream to Roon Ready devices, as well as Airplay, Meridian, Squeezebox, HQPlayer, and Sonos. You can read some more about why we don’t support UPnP here.
In this case, the only one of those capabilities the Mu-So has is Airplay, so I would expect any files over 16/44.1 to be downsampled.
Does that help @Helmut_Lehr? – are you still having issues switching sample rates? Can you confirm that these issues persist when the files you’re playing are stored on the same machine running your Core, as opposed to being stored on the Time Capsule?