I was able to make this work satisfactorily with DietPi + RoonBridge
After setting up DietPi, the brief steps were:
- apt-get update
- apt-get install ffmpeg
- apt-get install libasound2
- ALSA: linux sound system
I had originally neglected to install ALSA from dietpi-software (ffmpeg + libasound2 satisfied the requirements for the command line installer - roonbridge-installer-linuxarmv7hf.sh). However, the RoonBridge was not visible on the network, despite showing no errors in the logs, and successfully advertising itself. Suspecting that it wasn’t seeing the Pi audio interfaces correctly, I installed ALSA via the DietPi software interface, and now it works. It advertises both the analog (bcm2835) and HDMI (bcm2835 IEC958/HDMI) ALSA outputs to Roon.
I did not need to do anything special in Roon to configure it - it plays CD quality, HD FLAC and DSD files without complaint or problem.
I also enabled “PSU noise reduction” in dietpi-config audio options, which puts the CPU into powersave mode and disables the HDMI output.
The audio sounds “fine” - consumer grade 44.1KHz/16bit. Didn’t notice any difference with PSU noise reduction in my brief testing through Apple headphones.
Also added shairport via dietpi-software and that works fine with this configuration as well. It seems happy to play sound from both inputs simultaneously without conflict (a feature or bug, depending on your tastes).
It seems the AirPlay input is a little lower in volume than the Roon input, but haven’t investigated that yet.