Sony XM-1S Slim Series mono subwoofer amplifier 500 watts RMS x 1 at 2 ohms XM1S * mono subwoofer amplifier * 290 watts RMS x 1 at 4 ohms (500 watts RMS x 1 at 2 ohms) * low-pass crossover (50-300Hz, -12dB/octave) * variable bass boost (0-10 dB at 40 Hz) * switchable subsonic filter (15Hz, -12dB/octave)