Hi,
i've got a strange problem with plasma-pa/Volume Control.
I'm using a Xonar DSX and only got a 2-Speaker setup connected:
inxi -A:
Audio: Card-1 C-Media CMI8788 [Oxygen HD Audio] driver: snd_virtuoso Sound: ALSA v: k4.11.7-1-MANJARO
Card-2 Advanced Micro Devices [AMD/ATI] Device aaf0 driver: snd_hda_intel


when selecting "Analog Stereo Duplex" (or any other analog stereo), the volume control has no effect. Muting works, but changing the indicated volume doesn't change the real volume.
When selecting anything but stereo (for example "4.0 Surround + Analog Stereo Eingang"), everything works fine.

Can verify this issue with Manjaro KDE and Kubuntu 16.04 and 16.10, so it doesn't seem to be distro-specific.

For the most part, this is no real issue, but some games (for example Life is Strange or Dirt Rally) get confused by this setting and won't output voices unless is switch to stereo before launching and then back once launced - kind of annoying