Am Dienstag, den 21.10.2008, 08:32 +0200 schrieb Takashi Iwai: [...]
I didn't check the launchpad page yet, but did you set "IEC958 Default PCM" switch off? Or, start AC3 stream first, then analog stream.
The "IEC958 Default PCM" switch determines whether the SPDIF stream is assigned to the "default" PCM or not.
Thank you for bringing me on the right track! Due to my using an old driver there is no "IEC958 Default PCM" switch, but a little research discovered that you've dealt with this problem in February already (see http://thread.gmane.org/gmane.linux.alsa.devel/50989/focus=51486 ), and the proposed solution to set defaults.pcm.dmix.format S16 in ~/.asoundrc works for me.
I'm going to update the drivers anyways, but I'm confident that it will work now :-)
Again, thank you for your quick response! Tomas