Comment 2 for bug 1026331

The same, I can mute Master but I can't effectively unmute it afterwards.

Example:
* <Sound is on>.
* Open alsamixer.
* Mute Master with "M".
* Note that Headphone and Speaker don't appear as muted, not even with refresh ("L").
* Quit alsamixer and open it again.
* Note that Headphone and Speaker do appear as muted.
=> I.e. first problem is that the Headphone and Speaker were muted without the user requesting it, and without alsamixer getting notified about it.

* Unmute Master, Headphone and Speaker with the arrow keys + "M".
=> Second problem is that while they appear to be unmuted within alsamixer, the sound applet still shows my soundcard as muted, and I can hear no sound.
* Try changing the volume with the up/down arrow keys.
=> Again, while that appears to have an effect in the alsamixer UI, no sound actually comes out of the speakers, changing the volume doesn't unmute the card.

To sum up, muting either ONE of (Master, Headphone, Speaker) "secretly" mutes the other 2 ones as well, and unmuting them from the alsamixer UI doesn't bring the sound back.

Running the following does bring the sound back though:
amixer set Master unmute
amixer set Headphone unmute
amixer set Speaker unmute