XD600/6 - JL Audio 600W 6-Channel Class D Amplifier 600W 3/4/5/6 Channel Amplifier For superior noise immunity, RCA jack inputs On-board Crossover: State-variable, 12dB/octave Butterworth with continuously variable cutoff frequency selection from 50-500 Hz. Configurable as Low-Pass or High-Pass. Defeatable. Dimensions (L x W x H): 10.23 in. x 7.09 in. x 2.05 in.