after playing several big arse amps (Genz Benz 1200, Gallien 1001, Trace Elliot 600, different preamps with PA-slave-amp) I finally ended up with a Mesa Boogie 400+ and a Thunderfunk 750.
Both are too got to give them away.
The TF with two 2x12" SAD cabs (= 2 Ohm) generates the loudest, clearest, full bottomiest attack I ever experienced.