From reviews that i seen from the internet, i thought there should not be a power switch avaliable for the PM 4.1, but my PM 4.1 have a power switch located at the back of the Sub-woofer. When i switch off the power, the amp switch itself off totally, consuming no electricity at all. Is there modification done to my PM 4.1 or is it that there are different PM 4.1 avaliable in the market? And btw, i'm using the 230V version. Thanks