I'm considering buying this amp, but couldnt help realized that it seems a little bit underpowered. The Mesa site says this amp to be 550 watts and 4 ohms and 280 watts at 8 ohms. By the looks of this it seems like it may be barely keeping up powering just a 4x10. An 8x10 seems out of the question. Are Mesa amps "louder" per watt than most other? Whats going on!?