I havent used the six channel c-media chip but i say thier 4 channel is comparable to the Aureal Vortex 2 based cards. The sound was clean and decently crisp, the first versions of thier win 2k/XP driver had bad crackling problems but they seemed to of fixed it in later versions. The drivers are pretty plain jane compared to Creative's or Turtle Beach's, no selections to put sound to single speakers, it was pretty much just your plain old windows sound mixer with C-media smacked onto it.
As for speaker outs, the 4 channel i had seemed to be controled by windows, you change how many speakers you have in multimedia properties and it used the mic jack as your rear speaker jack instead.
Overal good for the money you pay for it, but not as good as a Santa Cruz or an Audigy.
CrackRabbit