all I get is clicks and hums. But if I start pavucontrol without changing anything in it the file plays just fine. If I close pavucontrol while it’s playing it continues to play normally. But the next time without pavucontrol I get the clicks and hums again.
Which desktop environment? Is pulseaudio running when you first try to use mpg123?
ps -A|grep pulse
Normally, I’d expect it to be active (but I’m using KDE where it is started at login). My thoughts were perhaps that by starting pavucontrol, pulseaudio is then started in your case?
If it isn’t active, it can be started manually with
Fair enough - that’s the pragmatic option. However, it would have been interesting to see if driver power management was at play, as we could have perhaps taken steps to inhibit it.
FWIW, I stumbled over an old Mac thread describing similar behaviour, and the quirky workaround suggested was to play a silent mp3 file continuously in the background to keep the audio system awake!