I'm a first timer here so thanks in advance for your expertise. I've installed a PA 660 4 channel amp and want to bridge it to my two 12" 4-Ohm subs in a box (1200W). I'm using only the two rear channels from my OEM head unit and they were connected to the front inputs on the amp (as is requested by the manual pg. 6 2Ch/4Ch Switch) and the output was bridged as per manual pg 11. The amp is wired in and receiving power, but I received no sound. I rearranged the output wiring from the bridged configuration to the front speaker output only and am now getting sound, but its not not even close to what I'm looking for in amplification.
How can I use the bridging configuration so as to get max amplification? Do I need to split the incoming 2 channel signal into 4 channel (front and rear) so that I can use bridging? Should the 2 Ch/4 Ch Switch be set to 2 or 4?