Comment 7 for bug 1171435

ports:
  analog-input-microphone: Микрофон (priority 8700, latency offset 0 usec, available: unknown)
   properties:
    device.icon_name = "audio-input-microphone"
  analog-input-linein: Линейный вход (priority 8100, latency offset 0 usec, available: unknown)
   properties:

  analog-input: Аналоговый вход (priority 8000, latency offset 0 usec, available: unknown)
   properties:

 active port: <analog-input-microphone>

Simple mixer control 'Line',0
  Capabilities: cswitch cswitch-joined penum
  Capture channels: Mono
  Mono: Capture [off]
Simple mixer control 'Mic',0
  Capabilities: cvolume cvolume-joined cswitch cswitch-joined penum
  Capture channels: Mono
  Limits: Capture 0 - 31
  Mono: Capture 31 [100%] [12.00dB] [on]
Simple mixer control 'Mic Boost (+20dB)',0
  Capabilities: pswitch pswitch-joined penum
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Mic Source',0
  Capabilities: cenum
  Items: 'Mic Jack' 'Front Panel'
  Item0: 'Mic Jack'

do mic boost really affected playback only ?

ARECORD

**** List of CAPTURE Hardware Devices ****
card 0: STX [Xonar STX], device 0: Multichannel [Multichannel]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

it is strange to use multichannel as device name , does it replay support multi channel capture ?

you have to ask the author why not implement capture source control to select rear Mic, front mic and line in