@flkin I have Euphony OS on custom build streamer, also have Sonore OpticalRendu streamer. Running in bridged mode, custom build contains Roon core, OR Roon Endpoint. I can also go Roon core on custom, Stylus endpoint on OR. Finally in unbridged mode, custom build only streamer, OR out of system, full Roon or full Stylus. I won't go through sound quality with each option, but running bridged mode, Roon core on custom build, Roon endpoint on OpticalRendu best sound quality, betters Stylus endpoint. As for running full Stylus, which I can do with and without the optical conversion setup with the Sonore equipment, user interface with Stylus terrrible vs Roon with my huge library. This to the point don't care if Stylus does sound a bit better. I can only say improvements in Roon sound quality directly correlate with system improvements, no sins of commission I can detect.
My theory as to Roon sound quality variations is Roon will sound best with powerful processor/low latency streamers since Roon requires much from processor resources. All the conveniences of Roon demands work from processor, work means noise. With my processor, 9 cores I'm often using only 1 or 2% of processor resources, this means low noise.