Can't go past 40% volume without being way too loud.
Why didn't you say so? All this voltage stuff is irrelevant. Your problem is you think that where the volume knob is pointed means anything at all. Relax. Where the volume knob is pointed means nothing at all. Or if you want you can tell people your amp is so incredibly powerful look how loud it is and the volume is barely cracked open. But seriously, where the knob is pointed is utterly irrelevant.
This is in stark contrast to the numbers on the dial, which are incredibly important. https://www.youtube.com/watch?v=4xgx4k83zzc
That's a joke, son. (I have to say that because audiophiles have no sense of humor.)