Pioneer GM-D9704 Stereo Amp Compact 4 Channel Class FD Car Amplifier 800w RMSGM D9704 4 Channel Class FD Car Amp. Compact 4 Channel Power An amplifier shouldnt take up too much space, especially in your car. This Class D amps might just be what youre looking for. It combines a 1 Ohm stable circuit, installation flexibility and a superior high power output. Speaker line input sensor Speaker line input sensorconnect your existing OEM unit without the hassle of add on adapters Variable LPF Variable LPFadjust your low pass filter