wiring a Line Out Converter

ive been doing some research on this. i have a 2007 nbs silverado non bosche, onstar and steering wheel controllers. i want to retain the stock H.U. my main question is, do i completely need to dsiconect the rear speaker wires from the speakers and connect them to the L.O.C or can i just keep the wires as they are and splice a wire off of the existing speaker wire and on to the adapter? im wanting to run 2-10" subs off of one single amp. im not wanting to run an amp for the stock speakers. any help? pictures if possible. 

you can just splice into them.  Fair warning though buy a nice line out converter and you may or may not be happy with it still.  They tend to introduce a decent amount of distortion into the system.  Depending on what brand you get it may come with a ground as well, make sure you use this.   Depending on if you have a standard cab or not I would consider just not running rear speakers this way you can control the amp input somewhat with your fade without worrying about sending to much of the music to your back speakers and causing them to distort.   The biggest problem in general is that for a tuned setup you typically turn "the bass" down for your midrange/high speakers and allow all of it to be directed to your subs.  With the line out converters though if you turn down "the bass" it turns down the input to your subs as well. 

ok. another thing. while i was doing some research, i found a post where it states that the closer you splice to the adapter to the speaker the better it is for the sound quality. can anyone back up that comment? i have a extended cab and it looks like a pain to just get to the speaker in the rear so i was planning on splicing into the wire right after the stereo harness.

there are pros and cons to both.  By doing it behind the radio, where it is honestly typically done except in vehicles where the speakers are on the rear deck, you then have a lot of power wires running around your converter, as well as getting the rca's back which now need to be ran on the opposite side of the vehicle as the power wire to the amplifier.   By doing it in the back however, you would have less quality because you are now relying on the factory gauge long length of wire to get to the back speakers.  You honestly will probably not notice a difference either way though as long as they are done correctly.   Helpful hint on splicing into the wires by the way, take a set of strippers and put them around the wire you are trying to splice into, squeeze just enough to cut through the insulation.  Holding the wire firmly in one hand, pull the strippers with your other hand away from the direction you are holding.  You might want to practice this a couple of times if you haven't done it before.  There is enough "slack" in the insulation that you can typically expose up to 1/2" of bare wire.  You can then take the leads from the line out converter and wrap them around the wire and solder the connection.   I would highly suggest soldering all of your joints and then using a high quality electrical tape over them, or heat shrink but heat shrink won't work with the way I just mentioned to strip the wire.  The little plastic splice connectors you can buy are garbage.  Those connectors alone can add problems to your system. 

location of the l.oc. isnt really much of an issue when adding just bass,also i would recommend using a pac-audio l.o.c. the sni-35 to be exact...

I think that is the brand I use to use a lot as well.  They seemed to much better thought out than a lot of the other ones I had ever used

If you do get a lot of noise, you can still purchase a noise filter from pac. Make sure you run the power wire and the rca's on opposite sides of the car/ truck. The coverters usually have a ground wire them on them also.  Sometimes grounding them helps, sometimes it makes it worse, sometimes it does nothing. I am not really sure why there is a ground on them, but you can try grounding it to see if it cancels any noise.

Great! all of this is amazing info. i think im gonna go ahead and give it a shot. any other things i need to look out for or not do? is there anything i might do that will screw up my controllers or anything? i dont belive so but i just wanna play it safe. thatnks again for the advice.

just make sure you are getting the right wires and the converter won't screw anything up.  If you grab it behind the radio, might want to research the wire colors before starting

rear speaker wires in gm vehicles are brown (+)/yellow (left) and dark blue(+)/light blue(right)......just remember dark colors are always positive in the rear in gm vehicles....fyi...tan (+)/gray(left) and light green(+)/dark green(right) are the fronts....