stereo upgrade - need help
I've got a 2007 outback, with the standard kenwood and 6 speakers. I want to add tower speakers, and possible a subwoofer.
To this end, I've purchased MTX tower speakers, a MTX 4-channel (300/900)amplifier, a deep cycle battery (my other is a standard starting battery), and a stinger 200 amp battery isolator. I've gone back, looked at several dual battery threads, as well as Amp installed, but am still unclear on a few things. My over-all goal is to allow use of the stereo, at times when the motor may be off, but also knowing that even when running, I may need the 2nd battery just to keep up with the new amplifier (the amp may draw more than the alternator is putting out).
1. I basically plan on keeping the kenwood stereo as is, with the exception of running 2 leads (rear left and right) to the new amp.
2. As for the dual battery - should the deep cycle be the primary, with the starting battery in isolation until key is turned? (that way I'd be able to run stereo (minus amp) when motor off, without to much drain).
3. Should the amp be wired to the 2nd battery (through an accessory switch), and what amp breaker should be between the amplifier and the battery?
4. WHat's the best way to run the cable to the speakers, and what cable should be used. I do have to lower and remove my tower for storage, so I was lloking at a weathertight 4-connector male plug, and a female adapter to mount on the boat. But looking into the wiring, the amplifier suggests 12 AWG, and the cable for a 4 conductor, 12 awg is over a 1/2 in thick. Is it permissible to drill that large of a hole in the tower to run the cable inside? It seems kind of large. Any suggestion/direction is most welcome, and as always, thanks for your help in advance.