Do you not have enough voltage in the rcas to run all your amps or what? Just to make sure were talking about the same thing.

If this is what your talking about, you want to have it as close to the start of the signal as possible because the sooner you can get the voltage up then you have more signal and less noise. Well I guess not technically less, its still there, but its lower in relation to the music signal (signal to noise ratio). If the rcas pick up noise on the way to the line driver, which is more likely the longer the run, then it will also amplify the noise. It will still work in the back its just not optimal. If you dont have noise problems it will probably be ok.

Or are you just asking if you can feed power to the unit the front from the battery in the back?