I have the U85 Premium audio set up. I don't think its setup how we thought it was. The gain control does not run the tweeters. It runs 2 extra voice coils in the 6x9'*. Subwoofer voice coils.

The front is easy.

For the front. Speaker level comes out of the head unit and splits both channels into 2. A left and right go into the Small amp (they one with the gain control). The other leads head off to the speakers themselves. Each speaker is 4 ohms and is wired parrallel.

-So depending on the resistance of the small amp. We're pushing our aftermarket head units below 2 ohms for the front channels. If you replace the 2 speakers and wire them into an aftermarket component system you can get that to 4 ohms. That should help correct some of the problem. Depending on the amp you'll be running closer to 4 ohms and what the aftermarket head units want. If it'* close it'll just run the amps a little harder but thats okay rarely are speakers perfect anyways.

For the back. This is a lil trickier. The sources from the head unit is basically broken into 2 on the left and 2 on the right. One left and one right go to the amp again. Now the other sources mirror the front. The Tweeters that fire foward are wired in parrallel with the 6x9. I know that the 6x9 voice coil is 10 ohms, i don't know about the foward firing tweeters.

- Now this is the big problem. When I find out what the tweeters are I can really deside what to do. But If you want to just use an aftermarket head unit and not have a seperate amp. You'll probably want to wire the tweeter in serial with the 6x9. If the tweeter is 4 ohms that will create 8 ohms. Most aftermarket heads want 4-8 ohms. But that also brings up the issue of running the head unit uneven. If they have 4 seperate amplifiers then it should be okay. But if its 1 4 channel amp that could cause some problems with uneven running.

Now this is the big weird thing. I don't know exactly what the amp does internally but I do know this. It runs a seperate voice coil in each rear 6x9. A 4ohm i believe. If must mix down all 4 channels into 2 sub outputs. This could make installing aftermakert subs easy. Just place those L and R channels into the speaker level of the sub amp.

I'll update this again when i do more measurements tomorrow. But from the looks of it these premium stereos (before bose) are a real bitch to work on if you want to keep all speaker positions. You could just not wire in the foward firing rear tweeter but then you'll loose some of your imaging. The front is fine. The rear is the bitch.

I was all over the wiring for the 6x9 woofer leads to run my subs a few years ago. It'* nice to use the stock gain control slider to control my subs.

The rear 6X9 speakers have dual coils, a subwoofer and a mid-range. I have never seen anything like that for sale.

Yeah i havent found any either. I'm going to run those power sub lines to an aftermarket amp. Maybe a Infinity Basslink. I just want something to accent not overpower and add weight. Cuase i am all go and no show.