Hey all, new member here, but a veteran bass player. Until now I've been playing on a REALLY old head & cab, like made over 25 years ago, and I'm ready to step up and buy something substantial. I'm torn between these three amps: The Mesa/Boogie M-Pulse 600, the Big Block 750 and the Ampeg SVT4 PRO. One thing I'm confused about are the power ratings of the Ampeg. Here are the power specs: RMS Power Output (2 Ohms): 600x2 RMS Power Output (4 Ohms): 490x2/1200 (mono-bridged @ 4 Ohms) RMS Power Output (8 Ohms): 300x2/900 (mono-bridged @ 8 Ohms) What does this mean? How do you physically "bridge" an amp/cabinet? An example configuration for each of the above cases would be appreciated, as would an impedance specification for each cabinet used in the example. Now, the Mesas give 600W RMS and 750W RMS, but I understand that the M-Pulse 600 is rated 600W at 4 ohms, while the BB750 is rated 750W at 2 ohms. Is this correct? The Mesas don't have any information on "monobridging", so I'm not sure how they compare to the Ampeg in that respect. Is it possible/recommended to bridge with the Mesas? Obviously power is a secondary concern to tone here. I play a 5-string Ibanez SR505, and I'm into playing everything from Tool and Pantera to Red Hot Chili Peppers to Victor Wooten and Stuart Hamm. Which amp would you recommend? Versatility is what I require, above all. That said, I'm worried about the somewhat limited EQ on the BB750. If I were to go with a Mesa, I'd probably go with the M-Pulse 600. Then again, rumours are that Mesa is planning to replace the M-Pulse 600 with the Big Block. Does this mean a better EQ for the 750? I also hear the Mesa cabs generally give much clearer tone, and fatter, cleaner bottom end (I'm planning on stacking a 2x15 Powerhouse with a 4x10 Powerhouse), than the Ampeg cabs. Any thoughts on this? Sorry for the long-winded first post, but I'm sure if there's a place to get all my questions answered, this is it. Thanks for your time, all.