Comment 46 for bug 1365769

previous driver allow you to change the volume from audio output by pcm loopback playback volume but the current driver set this gain to 0dB

Node 0x21 [Audio Mixer] wcaps 0x20050b: Stereo Amp-In
  Control: name="PCM Loopback Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=5, ofs=0
  Control: name="PCM Loopback Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=5, ofs=0
  Control: name="Front Mic Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=3, ofs=0
  Control: name="Front Mic Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=3, ofs=0
  Control: name="Rear Mic Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=1, ofs=0
  Control: name="Rear Mic Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=1, ofs=0
  Control: name="Line Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=2, ofs=0
  Control: name="Line Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=2, ofs=0
  Amp-In caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-In vals: [0x80 0x80] [0x80 0x80] [0x80 0x80] [0x80 0x80] [0x80 0x80]
  Power states: D0 D1 D2 D3
  Power: setting=D0, actual=D0
  Connection: 5
     0x2c 0x2b 0x2a 0x29 0x28