Sound issues with symphony of the night.

I have been working on getting Castlevania: Symphony of the Night to play and have fixed all but one issue. The music playback is erratic and will speed up and slow down randomly. I am using peops psx direct draw soft renderer for video and am using the following settings.

window mode 800x600
color depth 16bit
stretch to full window size
no dithering
use fps limit
use frame skipping
auto detect fps/frame skipping limit

and for audio i have been using pete's dsound audio driver 1.15 with the following.

volume medium
enable xa playing
1: high compatability mode
spu irq

this is the only one out of the four audio plugins that doesnt lag my video. the others are eternal spu 1.41, eternal spu lite 1.41, and epsxe spu core.

any suggestions on fixing the music? if i cant fix it i will just run the audio tracks on loop through a music player and change them when i enter the appropriate areas.