Oxygen Audio SPIRALM1.2KW Class D Mono Amplifier, 850W x 1 (O2 SPIRAL-M1.2KW) Nominal power in stereo mode @ 12,5V - 4 Ohms (WRMS): 1 X 475 Nominal power in stereo mode @ 12,5 V - 2 Ohms (WRMS): 1 X 150 W Nominal Power in mono mode @ 12,5 V - 1 Ohm (WRMS): 1 X 1300 W Frequency range @ +/- 3 dB (Hz): 20 Hz - 300 Hz Input sensitivity V): 300 mV - 8V