Dayton Audio SPA250 250 Watt Subwoofer Plate Amplifier Switchable 6 dB @ 35 Hz bass boost Measured power output: 156 watts RMS into 8 ohms @ 0.1% THD, 252 watts RMS into 4 ohms @ &lt; 1.0% THD Mono Class AB output stage for solid, well defined output Low-level, high-level, and LFE inputs connect to any system Manual, auto, or triggered on/off modes for compatibility with any automated system Variable gain, crossover point and switchable phase controls optimize room integration