Comment 53 for bug 936539

(In reply to David Henningsson from comment #39)
> > W: [pulseaudio] alsa-mixer.c: Volume element Master has 8 channels.
> That's too much! I can't handle that!
>
> I think the short-term fix would be to just ignore Volume element Master.
> Long term we could think about supporting it correctly.

1) some notebook with hda codecs (e.g alc260) which have stereo Master plaback volume control instead of the virtual master playbav volume
2) most multi channels usb audio card have these kind of playback volume control

http://mailman.alsa-project.org/pipermail/alsa-devel/2015-March/088833.html

numid=11,iface=MIXER,name='Speaker Playback Volume'
  ; type=INTEGER,access=rw---R--,values=8,min=0,max=74,step=0
  : values=54,54,54,54,54,54,54,54
  | dBminmax-min=-74.00dB,max=0.00dB