Clarity,power, most important CONTROL! The can drive every speaker around the globe without breaking up in clipping! [okay maybe the nautilus:-]

None...not even one the are easy to move not heavy at all! And the power is super!

These amps are the works! I`ve heard amps that are just as nice and detailled in sound...but the had one sorry TWO..Big problems compared to the Sphinx P12 monoblocks.. First thing: The were much more expensive Second:The were very big and bulky compared to the sphinx. The sound of these amps are amazing...i use them to drive one of the [audio]worlds most difficult speaker ever created..The ampkillers Infinity kappa 9 [0,8ohm@33hz] I`ve seen amps go into clipping that are priced [16000euros] with these speakers. The p12 are small very small compared to other amps with the same poweroutput..the can control even the most difficult speaker around without even breaking a sweat. I currently using the yamaha mx-830 stereo poweramp on the lows[BI-AMPED]..the p12 on the mid/high//everything sings now! No matter what the people say about yamaha...screw them...ik know how it sounds...PERFECT!