My two DAC+ installations work without any problems with Volumio since a long time. Now I'm using an official 7" Raspberry Touchscreen on one of them I discover serious problems.
System boots and I can use the GUI but no audio is played, most often the system does not boot at all and the screen stays black until the next try. Sometimes, let's say 1:10 tries, it boots and all works fine but this happens seldom.
I'm afraid the DAC+ is the suspect because all works fine when I select audio playback via the phone connector on the RPi board and not the DAC+.
On the Volumio forum there is a discussion going on and founder Michelangelo is watching too. I refer to that posting for all my tries so far, my username on that forum is VoluHans.
Does anyone have suggestions to solve this?