The specs claim S/PDIF out for connection to 'Creative digital speakers', but looking at the images it seems to be using an non-standard connector (mini-jack instead of RCA or toslink). Have you used the digital output? If it's a proprietary interface I'd have to buy something like this http://www.hdaudiovisual.com.au/mcpc/hda_x510.htm
which would take up a second expansion slot, not an option for my Silverstone HTPC case.
Creative seem to have a annoying reluctance to put standard optical or coax S/PDIF output on all but their extremely expensive top of the range cards. This is made doubly annoying by their total domination of the market, as there aren't many alternatives out there.
The M_Audio Revolution cards might do the job, a full set of connectors and in theory great linux support due to the Envy24HT chipset used. Anyone got experience with these, or other Envy24HT based cards?
An even better card might be the HDA Digital X-Mystique 7.1 GOLD, though I'm not 100% confident of trouble free use with ALSA. It's based on an evolution of the C-Media CMI8768 (which is supported by ALSA), the CMI8768+, which adds Dolby Digital Live (real time digital encoding). Anyone know whether this card currently works with ALSA?