Comment 4 for bug 882837

Ok, this is definitely a big audio bug. This is what I've experienced (no headphones, max volume):

1) Run alsamixer and open some music/sound file.

2) Try to mute (press M) the Master Channel.

3) Unmute it (by pressing M again): nothing changes, still cannot hear anything (= XF86Mute).
3.1) Decrease and Increase the volume level of Speaker Channel: voila! The sound is up again!
3.2) Randomly mute Master, Speaker and/or Headphone Channels.
3.3) Exit from alsamixer and run it again: despite what you muted all the channels above are MUTED! This is NOT a correct behavior.
3.4) Unmute all of them and "touch" the volume level of the Speaker/Headphone Channel: the sound is back.

I've also noticed that the pulseaudio system isolates Headphones from Speaker. I mean that if I have 100% volume and then plug headphones in, the volume will change according to the last value set while headphones were plugged! And once I plug them out the volume level goes back to the "no-headphones" level. Now: I don't know if this behavior is wanted but Ubuntu does not implement it and, pheraps consequently, isn't affected from this bug.

@Rich Lawrence: I read the help of pacmd and successfully got a correct mute/unmute CLI shortcut. The problem now is: how do I replace the combo X86Mute with a dual "set-sink-mute 0 0/1" depending on the current state? Thanks in advance!