Trying to get knoppix to play audio over the hdmi

So I got this core i3 system and I wanted to play audio over the hdmi.

Knoppix is awesome but I had a hard time figuring out how to set the default audio device.

alsamixer doesn't seem to have facilities for setting the default audio output.

aplay -l gives me this output:

knoppix@Microknoppix:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC892 Analog [ALC892 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 1: ALC892 Digital [ALC892 Digital]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 7: HDMI 1 [HDMI 1]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 8: HDMI 2 [HDMI 2]
Subdevices: 1/1
Subdevice #0: subdevice #0


and then editing the file /usr/share/alsa/alsa.conf

defaults.pcm.card 0
defaults.pcm.device 3

I set the defaults.pcm.device to 3 so that it will play over HDMI 0

alsactl init

seems to read the alsa.conf file to get things working, and youtube plays over the hdmi with iceweasel.

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edit:
I like to run knoppix on a flash drive with a persistent image and after changing the default.pcm.device to 3, I took the flash drive and booted it on another system. Then I got no sound on the other system which was totally baffling. Then I remembered that I had changed the default.pcm.device and resetting it back to 0, the sound came back. On that particular system, there is no device #3.