Comment # 13 on bug 913686 from Takashi Iwai

(In reply to Markus Zimmermann from comment #12)
> Disabling "Auto-Mute Mode" and then adjusting the levels of the mixers does
> not work as I expect it to. When I plugin the the jack in the dockingstation
> and my headphones they both have sound output and adjusting the mixers
> adjusts both of their levels.

If you want more finer volume behavior adjustment, report it to PA upstream.

The shared volume can't be avoided as it's a hardware limitation: the chip has
no individual volume control for all three outputs, thus one of them has to be
shared with another.  The mute/unmute could be done, though.