Something is fishy. It's probably a good amp, but someone is selling them by some modified Watts. The standard sets the wattage RMS into 8 ohms and both channels driven. 4 ohms for car stuff. Something always limits the power. I may have not done the calculation above completely right. In any event, the power supply plays a major role. Even so, take 5*0.62*60*2*1.4 is about 250 Wrms. That's the most you can expect out of the amp for BOTH channels using current as the limiting factor.