Kenwood Kac-8405 4 Channel 720 Watt Class Ab Amplifier + Cadence Wk42 Complete 4 Gauge 4 Channel Wire Kit with (2) Sets of Rca Cables
I haven't had any problems the amp.  The wiring should be considered more like 8g. I have it hooked to 4  6x9s  so it's not pushed very hard