What agarwalro said. Once I significantly treated my space, I immediately found that I was increasing the volume, because, well, I could. It now takes a lot more for the room's problematic issues do rear its ugly head.
I've even read that bass traps can measurably change in temperature after a lot of sound absorbing.
Once you are given the freedom to crank the volume a bit more, it is then that one becomes all the more appreciative of having speakers and amps than can indeed crank. I mean, I know it's all relative, but that's my experience.