Rockford Fosgate PM600X4 Punch Marine 500-Watt Class A/B 4-Channel Amplifier

In addition to 4-channel stereo mode, you can bridge both channels to create a high power 2-channel amp or run stereo speakers on the front with subwoofers on the rear in 3-channel mode. The variable HP/LP crossover and built-in Punch EQ allows for precise tuning of Bass frequencies and the Pass-Thru RCA jacks provide flexibility as your system grows and keeping Y-adapters to a minimum.

eBay