My DDC has USB selected (and connected to the Sonore UltraRendu), and it is connected to my DAC via i2s connection.
My DAC is connected via balances cables to my preamp, and preamp connected via balanced cables to my power amp.
The crazy thing is, the only physical connection that changed was to pull the USB cable from my NUC that is attached to the Denafrips Hermes DDC (and was working perfectly) and move it instead to the Sonore UltraRendu. I was literally playing music via ROON through the Denafrips Zone minutes before the change. Physically, it should be fine.
Again, no errors, the software seems connected fine, the music plays, amps are on, but no sound. Ugh.
Same thing when I bypass DDC and go DAC direct. Either way, the system recognizes the Denafrips, I can select it, adjust the volume, set up HQPlayer as a zone, select the zone, and play music.
That said, the signal path only shows source to HQPlayer while playing, it does not show the DAC.
Did you try disabling the denafrips as a zone in roon (leaving only hqplayer)?
In the UltraRendu web gui, when you click apps and then dac diagnosis (if I remember correctly, this is the path) do you see your dac listed as an output?