I can't tell the difference when CMSS 3D is on ?

I have an Audigy 2 ZS. When it is set to "headphones" and CMSS is off, it sounds fine except in games I have to make sure it is set to 5.1 or 7.1, otherwise it sounds horrible. When it is set to "headphones" and CMSS is on, it sounds horrible, like mono isntead of stereo for some reason. So I keep it set at 2.0/2.1 speakers, then in games I set it to either 5.1 or 7.1. I can tell when things are behind me because they are fainter than things in front of me. But when it is set the 2.0/2.1 and I toggle CMSS on/off I can't tell a difference. I have vista 64x, btw.

I am not an expert on sound but more than likely it is drivers which are out of date. I suggest Downloading the most recent version.IvanElk