yes it's never ending, then just went you think you get it, you wake the next morning and hate it. if so.. take into acount ear fatigue, pickups, wood / fret board / strings, how long the tubes have been heating up, room, and climate.
While you are voicing the amp try to decouple it from the floor, possible on foam yoga blocks or a chair.
It's all those little things that make hunting for the ultimate tone like finding the holy grail. Didn't the history channel say it was in florida? lol
Personally I gave up on that quest and went another route. Amp collecting, a tone for every occasion

Now instead of sinking all my time and $ into one amp I get to do it to a bunch of them and upset the wife with all the space they take up.