The PA 660 4 Channel Amp, 75 X 4 Watts is the perfect combination of rock solid reliability, advanced looks and ultra-high performance. It is capable of two-channel operation with a maximum power of 600 Watts when both the front and rear bridged channels are driven into 4 ohms speaker loads. The 4-channel, dual bridge-mono (2-channel), or dual simultaneous stereo/mono operation provide a variety of configurations and setups: 4-channel for front and rear speakers; 2 speakers and a sub; 2 subwoofers. The High-speed MOSFET switching power supply and high current bipolar output transistors pump maximum voltage and high current to your speakers or subwoofers. The variable input gain optimizes match with different signal sources.