I have a punch 360 that is not the power series. I ran it at 2ohms for 2 1/2 years straight without a problem. THe power series is a little better quality and a little more power. My 360 was tested at 490 watts according to it's birth record. A power would have given it more like 540 watts. Like fu-man said, better internal circuitry which makes the over all quality and power a little better.