Zapco ST-4X II 4-Channel 320W RMS Class AB Amplifier 4-Channel, Full Range, Class A/B | RCA and Speaker Level Inputs | Variable input gain control Variable electronic crossover | Auto-on with Speaker level inputs | Compact chassis | Variable bass boost control Power @ 4: 4 x 50 watts | THD @ Rated Power &lt; 0.5%THD | Power @ 2: 4 x 80 watts | Power Bridged @ 4: 2 x 160W RMS Signal to Noise Ratio &gt; 90dB | THD + Noise 60dB Frequency Response 15Hz to 30KHz 1dB | Input Sensitivity .25v to 5v | Dimensions in mm: 160(W) x 52(H) x 260(L) Overall: 160(W) x 52(H) x 302(L)