You can follow logs from a ssh session (sudo journalctl -f), or you can send a log from the Volumio UI (deviceIPaddress/dev). In either case, make sure that you cause the error message (by playing a track or whatever). If you upload a log then please include your username as well as a description of the problem.
I seem to have got past the “failed to open audio output” error by installing Volumio 2.129.
However, I’m not getting any sound out of the Justboom DAC Zero. I will have a look at the logs when i get home, as you suggest, and see if that helps.
I’ve had a look in the log:
volumio mpd[1769]: alsa_output: Failed to open “alsa” [alsa]: Failed to open ALSA device “hw:1,0”: No such file or directory
volumio mpd[1769]: output: Failed to open audio output
volumio mpd[1769]: player: problems opening audio device while playing “http://listen.radionomy.com/musicwire-livethesound”