I have the same card. I use headphone mode, not speakers. CMSS is different for speakers, so I don't know why people would use that. Are you using Vista/Win7 or XP?
Some people say, set the game to headphones/stereo. Personally, I think the sounds are muffled. I have the game set to 5.1. That is with Valve games though.
Some people say, set the game to headphones/stereo. Personally, I think the sounds are muffled. I have the game set to 5.1. That is with Valve games though.

