I understand setting the gains properly and everything just hope that the 6500's can blend well and keep up with the substage. And the Subs will both be ran at 1ohm on a nine.1 each. Not too sure why you need a second battery with your system. Are you wiring your subwoofers to a low impedance? A 240 amp alt maybe just enough for supply your vehicle and amplifier's need. Doesn't matter if an amp is 10 watts a channel or 1000 watts a channel proper gain adjustment is always necessary. Set your 200.4 gains accordingly.