The distortion thing has nothing to do with CMSS, its bad EAX support with the Live's. I had the exact same thing happen with my live as far as the sound distortion is concerned, espeically with sounds that were behind me. it just became quiet and muffled. UT2004, COD2, FEAR, BF2, all of them. Software sound sounded better, and crisper than EAX enabled with my Live. UT2004 was the worst, god did it sound horrendus in EAX. Once i got my X-Fi, all my problems were solved and sound becuase crisp and clear in all channels.
Its because Live's suck -period.