Hmm, it might be that I'm just super used to the beat, having played this map in VR hundreds of times. I didn't really have time to worry about sound balance too much.
You can set music/sfx volume in settings, but this is definitely something I'll keep in mind if I end up updating this later on.
No worries, I should have set it to reasonable levels by default. In fact, I remember deciding to do just that once I have a spare moment, but that never came =P