The root problem: for some reason, on boot, Ubuntu 14.04 disables (mutes) the S/PDIF output on my sound card.
This question and its answers indicate that sudo alsactl store
will store the alsamixer settings once I've unmuted the S/PDIF output, but on boot, the S/PDIF output is muted again.
In /var/lib/alsa/asound.state
(pastebin) there is one PDIF entry, which I've set to "true" and saved; this has resulted in solving auto-mute for my "Phantom Jack" but there's no other entry for the "true" S/PDIF in asound.state that I can manually adjust.
There's also an empty /var/lib/alsa/asound.state.lock
file (11 bytes, blank in gedit) in the /alsa/
directory. Is this something I should be dealing with?