At every rehearsal with my band it seems that his volume, his power, is very different each time. Sometimes i have to set the volume knob at 7 or beyond, but in other rehearsals 3 is enough!
I feel that also when i use the combo at home. Sometimes it roars and blows the windows, or sometimes i have to crank it up and it doesn’t seem to be enough.
I swear: i don’t have any ear damage

What could be the problem? To me it doesn’t seem some tube stuff or something like that…