I don't know whether this has been mentioned before; I didn't find it.

My problem is that in the cutscenes, the music is much too loud. I have just defeated the Primagen and couldn't understand anything Adon said in the end because the music was too loud. In sound options, I have music at about half the volume as voice, but to no avail.

On my playthrough shortly after release I had a similar issue; I had to switch to the N64 version soundtrack because the PC version music was way too loud. I'm pretty sure this was meanwhile fixed in a patch though.