Polk Audio PA D4000.4 (PAD4000.4) 800W RMS PA D Series Class-D 4-Channel Car Amplifier 125 watts RMS x 4 at 4 ohms (200 watts RMS x 4 at 2 ohms) 200 watts RMS x 2 in bridged mode (4-ohm stable in bridged mode) separate variable high-pass filters for front and rear channels (20-4000 Hz, 12 dB per octave) separate variable low-pass filters for front and rear channels (50-5000 Hz, 12 dB per octave) Small footprint. Dimensions: 6-3/4"W x 10-15/16"L x 1-13/16"H