I purchased an 340W Amp in addtion to a 10" 600W rated subwoofer. The Amp supports both High and Low speaker input. I am wanting to keep my Factory Head Unit (Deck) (1) What would be the best type of connectors, if possible to jack into my rear speaker's right and left runs; from them to my AMP. I will to keep my rear speakers working, I do not want them disconnected. (2) What size (gauge) power wire should I run up to the battery. (3) How should I get the power cable from the amp to the battery? What is the best path to take to it? Thanks in advance for any help!

JL Audio makes a unit that will convert speaker level to RCA outputs. If you don't want to spend any more money, just use connectors so that you get L+/- and R+/- to your amp from the rear speakers. I would use 4 gauge wire for a power and ground wires, but you might be able to get away with using 8 gauge wire. I always ran the power down the drivers side, through the steering boot, down under the drivers seat, and up into the trunk.