Adding this in /etc/asound.rc (more exactly /etc/alsa/pulse-default.conf on my Fedora box) work fine: pcm.a52 { @args [CARD] @args.CARD { type string } type rate slave { pcm { type a52 bitrate 448 channels 6 card $CARD } rate 48000 #required somehow, otherwise nothing happens in PulseAudio } } a52:0 is detected by PulseAudio and the encoded output shows as 'Digital Surround 5.1 (IEC958/AC3) in pavucontrol. I just finished testing all the changes I posted yesterday. Works flawlessly, I can switch from 2ch PCM over SPDIF to 5.1 still over SPDIF but re-encoded with a52, and unlike the passthrough case I can mix the multichannel content with alerts or system tones. The only bug I found is that if I change the individual volume on one of the channels, there's a ringing noise introduced, and it does not go away unless I kill the stream. Will prepare a set of patches, Colin it'd be great if you can merge them in git master. -Pierre