Are you operating in the correct SPL window for high-fidelity listening?

On my setup, the sound stage gets bigger with volume. The sweet spot is around 95db, it's crystal clear great dynamics, and you can start to feel it. 

Most of time, it's around 65-70db to not disturb the rest of the house. But when I'm alone, it's 95db and above. Have had it over 110db a few time, my ears don't like it, but the whole house can feel it. 

IMHO, if you have a volume knob that changes resolution of the signal, you have a crap pre-amp and should get a new one. The volume knob should just adjust voltage gain to the amp, it should not change any part of the signal other than gain.

I generally listen 65 to 75 db. My wife likes it a little louder. I recently went to the Show in SoCal. I was amazed at how very loud the exhibitors played the music. Some of the rooms were just too loud to enjoy. Particularly in the smaller rooms. The Show was very good and a great learning experiance. 

Style  of music matters. An acustic guitar or violin around 70/75. A female Jazz singer or trio,,,75 to 80 db. Some rock or EDM 85 to 90.

I’ve been a pro musician since the 60s, and I’ve learned that there is no bottom line regarding level. After years of hurting people with my trusty JBL festooned Twin Reverb with a Tele or Les Paul I switched to various smaller amps pointed at my ears and miked up appropriately. Still loud for me, perhaps not so much for you. I’ve also spent plenty of time in studios and as a live concert mixer and, again, there’s no bottom line for level...live I just want things to sound good and clear. I spent an afternoon in the 70s watching Glynn Johns mix and it was so loud I think I suffered some hair loss. At home all hifi level is mood based and it seems silly to try and quantify that...only play it loud if I need to hear something from the next room.

I’m listening at 66db now which is optimal for me when I am not constrained by other people or nighttime situations.