Cadence Acoustics XAH400.1B Class AB 850 Watt Mono Block Amplifier 4 Ohm RMS Power: 300W x 1|2 Ohm RMS Power: 425W x 1|Peak Power: 850 Watts Minimum THD: &lt;0.1%|Frequency Response: 10Hz - 250Hz|S/N Ratio: &gt;97dB Damping Factor: &gt;160 @ 100Hz|Input Voltage: 200mV - 8V Dimensions (L x W x H): 12.8" x 10.5" x 2.6"