I'm using xfce 4.6.6 (xubuntu 12.04).
PulseAudio fails to restore volume(every boot 100%) of my 5.1 usb headset cm106 (http://imm.io/nKZK),
i decided to switch xfce4-mixer to use ALSA mixer (alsactl and amixer work fine so i could use them to restore last volume)
see http://imm.io/nKSr and http://imm.io/nKSS.
and now xfce-volumed(media keys) uses correct mixer(configured ALSA) but indicator applet still uses different mixer, perhaps pulse.
I've spent a lot of time trying to fix it myself, but now i'm stuck.
Try to set manually keyboard shortcuts for changing volume, with the following commands:
* Increase volume:
amixer sset 'Master',0 5+ unmute
* Decrease volume:
amixer sset 'Master',0 5- unmute