I can't draw a schzmatic on the puter....but on the receiver all the ports for every channel are wired in parallel....in other words all the powers are wired together and all the returns are wired together....only the signal is wired seperatlely....so if you run 2 batteries through their own switches and hook the batteries to any unused ports on your receiver then that is parallel where the voltage remains the same.......two switches with two batteries so you can shut each battery off......
There is one thing I have forgotten to mention...if you use 2 batteries they must be the same voltage and same mAh rating