So I've got an ST1 and want to toss in an amp and a sub. I'm keeping the stock head unit for the time being and was curious if I could just jack into the rear speaker wire with a line out converter? I've been out of car audio for probably 15 years now, so a lot has changed since I use to mess with it. If there is a better option then the line out converter, please advise. I'm not trying to drop big cash nor have competition sound. Just want some added "bump in the trunk". I've got an amp and speaker laying around needing a home...if they still work...lol.