Comment # 10 on bug 1193644 from Michal Suchanek

So here is the deal:

The controls are utterly broken.

There is no way to unmute the card.

There is supposed active output - when headphones are plugged it's headphones,
otherwise it's speaker.

When supposed active output changes the output the is not supposed to be active
is set to level 0 and muted (would be OK if the routing worked correctly ...).

Muting master mutes supposed active output.

Muting supposed active output mutes master.

Unmuting anything does not unmute anything else.

-> to unmute card you have to know what's supposed active output, and unmute
that output and master.

Speaker output is speaker mute * headphone mute * headphone level

 -> when any switch happens speaker is most likely muted