SO all my amps are at least at waist level now. Nothing on the floor.
All my amps are properly matched, some with Weber impedence matcher, which is even more certain.
I found a sweet spot at low volumes. Beautiful, balanced, thumpy, with just enough high end. When I raise the master only, it seems to change up my EQ curve in a very unbalanced and unpleasant manner. On the gain channel, an increase in master volume upsets the entire EQ, which is understandable, but it seems MUCH harder to find a proper EQ balance than it was at low volumes, even with PLENTY of headroom left. All these years I thought I needed to crank my amp to get to the sweet spot, but I am now having the opposite experience.
I will go back to the drawing board tonight