Go for a used GenzBenz GBE 1200. Those mighty mofos spew put 550 Watt @ 8 Ohm, 1000 Watt @ 4 Ohm and 1200 Watt @ 2 Ohm.
There are two seperate channels, a Solid State and a Tube Channel, and you are able to mix the channels. The Solid State channel is known for its stellar cleans, the tube in the Tube Channel is for saturated sounds. Every Channel has its own 5-band - EQ, there are several global filters to make your sound even better.
I use my GBE 1200 now for about 8 years, I bought it used, and it never let me down. It fires up my Tecamp L 810, a cab that is able to handle 2.400Watt thermically with 4 Ohm. Wow, this rig is so absurd loud, I never needed a second cab - when playing with two gitarrists who use two 100 watt full stacks, what makes me "fight" against 4 full stacks on big stages. O man, praise and all hail to the man who invented Master Volume Gitar-Amps.
Later I bought the smaller brother, the GBE 750, and this one is loud enough for any situation I use it. The only difference between this one and the big one ist the power amp, otherwise they are the same - but the GBE 750 has only 2 HE what makes him fit into smaller cases. With 400 Watt @ 8 Ohm, 625 Watt @ 4 Ohm and 750 Watt @ 2 Ohm he might read less powerfull as the GBE 1200. But I am able to assure you, that this "little beast" is as loud as I need it in a loud heavy metal band when it fires up my Tecamp L 215". Or my second Tecamp L 810".
This have been said, I have to add, that even that the GBE are good with 2 Ohm loads, I never had the idea of using both of them. A cab with some cone surface and good SPL is all you need to make your amp heard, even in a loud band.