# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: PCH [HDA Intel PCH], device 0: ALC671 Analog [ALC671 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

/etc/asound.conf

pcm.dmixer {
	type dmix
	ipc_key 1024
	ipc_key_add_uid false
	ipc_perm 0660
	slave {
		pcm "hw:0,7"
		rate 48000
		channels 2
		period_time 0
		period_size 1024
		buffer_time 0
		buffer_size 4096
	}
}

pcm.!default {
	type plug
	slave.pcm "dmixer"
}