I was thinking about putting a sub I have from an older car that we don't use anymore into my Koup. I know you need a line out converter, but I found 2 different kinds. Which one do I need? Scosche LOC80 2-channel line output converter - Hands-on Research at Crutchfield.com or Audiocontrol LC2i 2-channel line output converter for adding amps to your factory system at Crutchfield.com I'm thinking it's just the first because I've never seen a stock system without an amp have amplified signals which is what the second one is meant to handle. Just trying to make sure I don't mess anything up. Thanks