I have two sound cards, one attached to pc speakers and one attached to a sound system in another room.
Following instructions on the alsa project wiki, I am trying to use two sound cards (V8237 and CA0106).
I configure my ~/.asoundc but I still can't manage to send a sound to both cards at the same time. Below is my ~/.asoundrc content.
When I tested directly the ca0106 card (hw:0,0) with a play, it didn't work so I thought it might be some sort of rate or conversion problem. I added the pcm.via and pcm.audigy in my asoundrc file and then, when I test each card individually ("via" and "audigy") with aplay it works well.
When testing the "multi" pcm with aplay (  aplay -vD multi question.wav ), I get the following error
aplay: set_params:959: Nombre de canaux non disponible (Channels count non available)

Any help or suggestions are welcome

~/.asoundrc content
pcm_slave.via_rate {
        pcm "hw:1,1"
        rate 48000
        channels 2
pcm.via {
        type plug
        slave via_rate
pcm_slave.audigy_rate {
        pcm "hw:0,0"
        rate 48000
        channels 2
pcm.audigy {
        type plug
        slave audigy_rate
pcm.multi {
    type multi
    slaves.a.pcm "audigy"
    slaves.a.channels 2
    slaves.b.pcm "via"
    slaves.b.channels 2
    bindings.0.slave a
    bindings.0.channel 0
    bindings.1.slave a
    bindings.1.channel 1
    bindings.2.slave b
    bindings.2.channel 0
    bindings.3.slave b
    bindings.3.channel 1
ctl.multi {
    type hw
    card 0