The power amplifier provides 3600 Wpeak power and offers features found on the more expensive LX subwoofers such as the Cardioid Preset mode switch which offers specific signal treatment for easy set-up of pairs of systems in cardioid subwoofer applications. The system includes two balanced inputs (A-B) with stereo HPF (100 Hz) filtered output connections for satellite systems. Defeating the HPF filter offers stereo “loop thru” connections. The variable LPF crossover ranges from 100 Hz-160 Hz. A gain control and polarity reverse feature increase user control over the system.