I have a 2007 jaguar x type 3.0 auto
It had navigation. it does not have a factory sub and it is not an alpine system.
If I want to tie into the door speaker wires for a signal so I can add a sub where is the easiest spot to tie in at.
I have an alpine amp and a 10"
The amp has high feed inputs so I can run right into the amp.
I was going to use the cigarette lighter wires as my amp turn on.
Any help with pictures would be greatly appreciated.

 

I don't think that wiring it in like that would be the best idea. If you put it in a series it will increase the ohms and result in less power going to the speakers.
For example I have 6 speakers on a 4 channel amp in mine. The front two channels each have one speaker at 2 ohms. So my gain isn't up very high for those. The rear channels have 2 speakers each. Each speaker is 2 ohms, so with 2 in a series the amp sees 4ohms. Which is double the resistance so my gain is double what the front channels are.
So theoretically, depending on how it's done you'll get about half the volume from the one that's tied into.
I would use a factory radio adaptor, allowing for more channel outputs and connecting to amps

 

Do you have a link to a good factory radio adaptor.
Also do you know if there is a write up on doing this.

 

is this what your talking about?
Scosche LOC90 High Low Level RCA Lineout Converter 2 Channel Sub Control LPL | eBay

 

I'm not a fan of scosche. They tend to be on the cheaper side.
But that's not exactly what I'm talking about. Have you ever been on crutchfield? They're way over priced, but a good resource to find what you need.
http://www.crutchfield.com/g_318850/Factory-System-Integration.html
There's the listing of processors for factory radios to amps.
http://www.crutchfield.com/S-Zm5f13fIGUD/learn/learningcenter/factory/sound_processors.html
Also read that. I've never used one because I have an aftermarket deck. But it's as easy as cutting and connecting speaker wires. The hardest part would be finding the layout of what wires are what

 

I'm on my cell phone so I guess the links didn't work. Just copy and paste
Are you adding anything else? Or just subs and an amp?

 

Thanks for the quick reply. I'm just adding a sub and amp.

 

Yea no problem
There's some that should split it all to 6 channels so you can have your speakers wired in, and they should sound better being filtered, then your amp from the other two channels. It can be pricey though. I find stuff on crutchfield then buy on eBay or Amazon.