Kenwood KAC-9103D Mono subwoofer amplifier 900 watts RMS x 1 at 2 ohms mono subwoofer amplifier 500 watts RMS x 1 at 4 ohms (900 watts x 1 at 2 ohms) variable low-pass filter (50-200 Hz at 24 dB per octave) bass boost (0-18 dB at 40 Hz) subsonic filter (15/25 Hz, 18 dB/octave)