A 200W valve amp can put out 200W of clean tone, but crank it a bit more and you can get a lot more volume with a pleasing overdriven sound. Solid state amps don't sound too good when pushed past their limit, hence why some talk about 'valve' watts. But if you can't get enough volume out of a 200W valve rig and 4x12, there must be something wrong! any venue likely to need that much volume will have PA reinforcement that will reduce your amp to a mere on-stage monitor.