I have a two year old Digi+ Pro on a RPi 3B, feeding into the co-ax input of my Quad Vena 2, using the standard RPi PSU and until recently running Volumio to stream Tidal, Idagio and files on NAS.
A while ago I started getting occasional dropouts, maybe half a secong every half hour or so, but slowly becoming more fequent. Then I found that on start-up occasionally I would just get brief blips and pops of music, and would have to re-start.
More recently I've switched to Roon, running the core on a fanless Lenovo PC and using the RPi as the enpoint via Roopieee XL, but the dropouts are still there and are getting worse.
In desparation I switch to feeding the USB output of the RPi to the USB input of the Quad, with the Digi still fitted but not connected to anything. Bliss. No dropouts at all in two days of solid listening.
Am I doing something wrong or have I got a duff Digi? Installing Volumio and subsequently Roopieee are about as far as my knowledge will take me. I dont know where to start with fault finding these things!