Used rarely. Features Enclosure: The PSW-550 contains a single 8" long-throw, direct-radiating subwoofer driver with a rubber surround. The enclosure is magnetically shielded so this subwoofer can be placed in close proximity to your TV or video monitors. High-current Power Amplifier: The 8" driver is powered by a high-current 100-watt amplifier. Power Port Bass Port: Contains a downward firing Power Port bass port, designed to give you deep bass and high acoustic efficiency with low distortion. Auto On/Off Circuit: The auto on/off circuit automatically turns subwoofer on when it senses a program signal and turns off the amplifier after approximately 15 minutes without a signal. LFE Input: In addition to the left and right line level inputs, this unit includes an unfiltered LFE input for use with source units that have a low pass filtered subwoofer preamp output jack; the LFE input is a single RCA input.