I'm looking at getting a JBL or Infiniti powered sub for my 4th gen, but was wondering if I can run high-level inputs off of the rear speakers? Does the Bose headunit put out enough power even though there are amps on all the speakers? Also, which wires do I tap off of, since they use differential amplification?

 

Bose already puts out low level outs just tape the signal wires and go straight into rca's (splice into the rca's).

 

Ah, so this is why they put an amp on each speaker.

So I need to buy some RCA jacks, and then splice them in BEFORE the amp? What a mess.

 

Yup and nope thats not why they did it. It's just a bose quirk to make it more difficult to go aftermarket, which really, it isn't.