There's a notable problem in psx drivers regarding the sound, that affect at least most of games which I tested and maybe could be simple to solve.
Music tracks seens be very louder than it should be, even drown out the sound fx and voices in some cases.
I don't think this is a bug, but any kind of wrong configuration in the SPU driver.
Unfortunatelly, I don't understand very well how the SPU driver works to try to fix, then I'm posting it here for anyone that's more capable, to please give it a look.
I can give various good examples that make this issue easier to grasp, such:
-Tony Hawk's Pro Skater 2
-Spyro the Dragon 2
-and various others