hiya just installed an 800 watt amp running 2 subs. i got a wire from my battery with a fuse on it running to the amp. then a phono lead runnin from the radio to the amp connected to the rear speakers terminals on the amp. then an earth wire running from the amp to the car body. the speaker wires from the subs to the amp. and 2 fuses at 25 amps which are intact. but i got no bloody power!!!!! can any1 tell me why?