loc and speaker off same lead

I have searched all over the place to find an answer to this and haven't had any luck. My car has a 3.5" and 6.5" in the door and I would like to run the 3.5" off of the stock head unit and the 6.5" off of an added amp. The problem is that I have to use a line out converter to feed the amp. Is it possible to wire the 3.5 off of the headunit and then off to the amp? Should this be wired in parallel or series? If the 3.5 is a 4 ohm speaker, what resistance would the head unit see? Thanks in advance.

Ok ..Hold on...Your just hooking up a LOC...Dis-connect rear speakers that are going on amp...Connect the LOC ,...Pos to pos...neg-neg to the leads you dis-connected for the rear speakers...way over thinking that...Are you amping factory speakers...?M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

OH...BTW ...Year,Make,Model...?M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Since the input impedance of most LOCs is very high, (on the order of 1K ohm or so) wiring it in parallel with the 3.5's will not be an issue. It will drop your impedance a little bit, but it'll still be so close to what it was...It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

There are 3.5s in the door as well as 6x9s (front doors). I was planning on using 6.5 comps to replace the 6x9s and keep the tweeters close to the mids for better imaging. I've also got some decent 3.5 coaxials that I'd like to use where the 3.5 tweeters are in the doors. I'd like to keep the 3.5s running off of the head unit and level match them with the gain of the LOC or the amp. This is on a '06 Toyota 4Runner Sport without the JBL.

Thanks haemphyst. I think that's the answer I was looking for. I'm probably going to just give 'er a shot and see what results I get.

Chances are the factory amp has a built in crossover, it sends Bass,  Midbass and lower midrange signal to the 6 X 9, and upper mid and highs to the 3.5s.  Whichever speaker you connect the LOC to will only send those frequencies to the amp.   

I'm not sure if that's true in this case. The wiring runs from the head unit to the 3.5, then to the 6x9. It's all off of the same channel.