Kenwood KAC-9102D Car Audio Amplifier "7500 watt" Questions

...to stablize the power supply but the amp will still shut down after a while. I'm running one mtx 7500 12" at 4ohms the recommend power is 400 watts, with this amp I'm pushing 500 watts to it would ...

...watt Power Acoustik Gothic Amplifier and two 12 inch MTX 7500 superwoofers. When I go to hook up both the subwoofers, it seems like the subs won't work as well, but when I only hook up one sub, it ...