Comment 7 for bug 1498129

http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=src/conf/cards/USB-Audio.conf;hb=HEAD

for usb audio device 0 is default device for iec958

lsusb -vvvv

pulseaudio does not support multi channel volume control

Simple mixer control 'Speaker',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right - Rear Left - Rear Right - Front Center - Woofer - Side Left - Side Right
  Limits: Playback 0 - 127
  Mono:
  Front Left: Playback 107 [84%] [-20.00dB] [on]
  Front Right: Playback 107 [84%] [-20.00dB] [on]
  Rear Left: Playback 107 [84%] [-20.00dB] [on]
  Rear Right: Playback 107 [84%] [-20.00dB] [on]
  Front Center: Playback 107 [84%] [-20.00dB] [on]
  Woofer: Playback 107 [84%] [-20.00dB] [on]
  Side Left: Playback 107 [84%] [-20.00dB] [on]
  Side Right: Playback 107 [84%] [-20.00dB] [on]