I need help get rig of this " THUD " sound making from Subwoofer everytime I turn on receiver. I have Kenwood receiver with AC Outlet so I plug subwoofer directly to the outlet on the back of receiver. I alway leave subwoofer on so whenever I turn on the receiver then subwoofer would turn on also. This THUD sound always happend even I set the subwoofer sound level to the lowest, only one possibility to get rid of this thud sound (for me) is to turn subwoofer on manually. This subwoofer is a cheapo one so there is no Auto on/off switch with it (the another one I have doesn't have this problem becuz I use AUTO on/off. So anyone know how to get rid of this annoying sound???? Thanks in advance. One more question, Is it safe to leave Subwoofer on at all time. I' m thinking about plug subwoofer to household outlet instead of AC outlet from receiver. My concerned is about life of subwoofer and cost of electric bill.