I'm running a Sansamp RBI into a Yamaha P5000S parallel into two 4-ohm Acme Low B2 II 2x10's. In most instances I'm running through the PA. While I'm very happy with the quality of the sound I get from my MM Sabre active and Fretless Active jazz bass with this rig, I'm disappointed in having to crank the Yamaha amp and crank the RBI to get a decent stage volume and, volume in general. I thought by upgrading from a QSC RMX850 to the Yamaha, I'd have more headroom, but I'm finding the difference marginal, even though the Yamaha runs twice the power (750W/side) than the QSX RMX850 (300W/side). I've heard about the Acme's wanting juice, but c'mon, more than 750W? Would upgrading the amp further really solve the problem, or just put me at risk for frying the Acme's? Any other thoughts or recommendations?