Ah, right, I hear it indeed. Seems I just don't like distortion then ;-) Thanks for updating it with volume control. I will have a go at the dev branch (if I manage).
However, I just finished the first 'dimension'! I noticed two things of which one might be deliberate.
Spoilers below
On the level where you first see the heart, I could fire my shotgun through the surrounding wall to kill the blood vessels around the main heart.
I noticed (only once) that my shotgun bullets passed through the very fast bleeping virus like landmine.