I got a sub I want to put on my stock Bose cd player. I have the adapter to turn speaker wire inputs into RCA outputs for my amp to run my new sub. My question is which wire is the stock sub wire. I want to draw my sounds from my stock sub instead of juss any other door speaker which makes good sense to me. Instead of getting sound from any door speaker I'm gettin it from something that is already picking up the lows, correct?