You'll need a newer kernel, then. There was a problem with the amplifier initialization code. I could swear that was a REALLY old issue, but RH does maintain their kernel fork a little oddly at times.
The ONLY GTXP drivers are in the kernel itself (OSS/free), a pay-for-service (OSS/commercial), and in ALSA (pretty large PITA to DL/install, for a non-guru).
If you can't upgrade your kernel, you'll be out of luck for now, unless you feel like trying ALSA.