asound.conf

pcm.!default {
  type asym
  playback.pcm {
    type plug
    slave.pcm "output"
  }
  capture.pcm {
    type plug
    slave.pcm "input"
  }
}

pcm.output {
  type hw
  card "usb_soundcard"
}

ctl.output {
  type hw
  card "usb_soundcard"
}

ctl.!default {
  type hw
  card 0
}

pcm.dmixer {
  type dmix
  ipc_key 17
  ipc_key_add_uid true
  slave {
    pcm "output"
  }
}

pcm.dsp0 {
  type plug
  slave.pcm "dmixer"
  slave.rate 48000
}

pcm.dsp0s {
  type softvol
  slave.pcm "dsp0"
  control.name "Media"
  control.card "usb_soundcard"
}

pcm.dsp1 {
  type plug
  slave.pcm "dmixer"
  slave.rate 48000
}

pcm.dsp1s {
  type softvol
  slave.pcm "dsp1"
  control.name "Nav"
  control.card "usb_soundcard"
}