I would try installing the AHI sound hack that lets you use your sound card in the pc instead of the emulated paula. There is a program on aminet that allows you to divert paula sound to ahi as well..
You have to install AHI first though.. AHI is hardware independent sound. Works great with my AC97 and SoundBlaster Live! 5.1 with a little tweaking. MP3s play great using AmigaAMP with ahi enabled.