I'm keeping my stock head unit, but upgrading all the speakers. Question is, I have a line to RCA converter. Which wires do I patch into to get the Head unit speaker R and L out? And do I use the Head unit ground also or just ground it to the body?

 

If I remember correctly, you can still use the ground from the HU. As far as signal, you can use the front R and L to hook up to your line-RCA converter. In all actuality, it makes no difference whether you use the front or rear R/L for signal acquisition. It's all the same once it passess through the line-RCA converter.

 

I've found the wires in the service manual. Question now is do I need 2 line to RCA converters? Fronts and rears are seperate lines.