my trusty 10-year-old SoundBlaster Live! works very well on linux, but not at all on Windows 7 (alternatively: very crappy on win7 with an inofficial driver that likes to eat sound samples).
My onboard sound works very well on Windows, but cannot do surround on linux because of some "universal jacks" that double as speaker-out, line-in, microphone and whatever, and I haven't found a way to configure them to "4 channels + line in" on linux. But I'm sure glad the manufacturer could save 20 cents by not adding three more actual jacks.

Cue an asinine contraption of audio switches and everything. It works..ish, but has it's problems.

Now my 4.1 speaker system starts faling due to old age, and one can only buy 5.1 systems nowadays. New soundcard it is. But which one?
  • 5.1
  • must work on linux with in-kernel alsa
  • on linux all channels must be individually adressable - I need to route some (stereo) apps to front right and rear right channels, because my projector points at the wall between the two corresponding speakers (should work, unless the card does some fake-stereo-upmixing. It certainly works on the SBLive).
  • hardware mixing would be nice, even though I'm not much into wine gaming since I reinstalled windows.
  • must work on windows (duh!), for games. No fancy DRM crap needed.
  • must have a working line-in (to connect my Wii). Recording via the SBLive results in some very poor sound quality for unknown reasons.

Suggestions? Field reports?

Going with a creative card again may be the safe way, but
this only claims support for SBLive, Audigy 2 and Audigy 4, none of which are available at my favorite vendor. Said vendor offers a nice, cheap "Creative Sound Blaster 5.1 VX", but google find some results with "works" and some with "doesn't work". Meh.

Another thing: some vendor is telling me that my reproductive organs lack magnitude if I don't buy a digital system. As far as I understand, this would digitally encode the 1m of cable between my computer and the subwoofer, but then it's converted to analog anyway and sent across 4m of wire to the speakers. Are there any actual advantages of a digital system (besides having a copy protection bit in there)?