I've gone and confused myself about adding a 2nd battery...

[beedish]

David; to paraphrase, you're concerned that the system trying to equalize the voltages between the H/U and the amps would introduce 'noise' into the output?

If that's the case, it shouldn't be a problem to change the power source over to the new battery for the H/U. My only question is that I have a red (power), black (ground) and yellow (constant power) to the H/U. All else is through RCA's. I assume red to positive terminal and black to negative terminal of battery #2; but will the yellow go to the positive terminal of battery #2 as well, or can i leave it connected to battery #1? Or is it one of those cases where 'you're already moving the others, just move one more...' ????

Edit: Is it a smart decision to re-route with shielded wire to avoid any possible interference?

Edit #2: Just realized the radio is switched; so would the red accessory wire to the back of the H/U stay in place and it would be necessary for me to find the hot lead into the switch and re-route that to battery #2??