[SilverMiner]

Ohhhh - you know, I kinda wondered if that wasn't actually what you were asking, but didn't respond that way because it isn't commonly done that way. May I ask why you are going down that route?

I have no good answer on how to do this as I've never bothered to try, but I'd suggest doing full internet searches on whether or not OEM radios are even capable of driving multiple speakers. I'd imagine they'd have to be in series, but who knows, it might need to be in parallel.

Please do report back if you are successful and happy with the result - I'd learn something that way. Congratulations are in order though for posting this in the correct forum. I've noticed many who haven't figured out how to find the Audio stuff now that it is sub to the main Electrical.