how to setup a Volumio system with a digital and an anolg output ?
My way : I plugged a Digiberry onto a Pi3 and added a JustBoom DAC https://www.justboom.co/product/justboom-dac-hat/
The quick-and-dirty connected test setup you can see here :
For testing I took the USB power from the PI. According to my first tests the DAC does unexpectedly fairly well although supplied from the PI. Obviously the voltage regulator on the JustBoom DAC makes a very good job.
It remains to be seen if a linear PS can do better than the switching PS I used here.