I just finished my install, and have some issues with the speakers cutting out. I have all 4 interior speakers on a 4 channel, and the sub on the bridged 2 channel. when i roll down the windows, and sometimes even just hitting the brakes the speakers cut out momentairly. also there is a slight hiss from the speakers when theyre turned down. the battery and alternator are both fairly new, and the system only does about 800w RMS. what could the problem be? Thanks for the help!