ALSA

5.1 Surround Sound through S/PDIF-Output (preparation for PulseAudio)

File: /etc/asound.conf

# Encode AC3 -> Directly on hardware
pcm.a52 {
    @args [CARD]
    @args.CARD {   
        type string
    }
    type rate 
    slave {  
        pcm {
            type a52   
            bitrate 448
            channels 6
            card $CARD
        }
        rate 48000 # Otherwise nothing happens in PulseAudio
    }
}
# Default ALSA Device is pulse (for Flash Player etc.)
pcm.pulse {
    type pulse
}
ctl.pulse {
    type pulse
}
pcm.!default {
    type pulse
}
ctl.!default {
    type pulse
}