I have a PSB Image series of speakers and Harmon-Kardon amp. My problem started when I connected the ICBM into the system. After that when the system is shutdown the subwoofer will make a large thump. It has a circuit that detects a signal and if none is present after a set time it shuts off same for turn on. It was fine and is fine when the ICBM is not in the circuit. I tried turning the wall wart around to change the polarity but no difference. Any clues would be appreciated. Thank you.