Have you just done a plain old reboot (soft reset)?
Try pulling the battery out for a minute or two...
If you have messed with the audiopara file maybe you could try a stock audiopara file...
I don't have one, I'm on a titan, but it's out here, search..
Good luck though!
edit: audiopara thread may help...
http://forum.ppcgeeks.com/showthread.php?t=41385