Do stock radios have preamp output on one of their plugs?

[thomash85715]

Moving closer to putting a powered sub in the trunk of my 08 MGM LS but hoping to extract preamp output from the factory head unit rather than use the power amp signal to the speakers. My radio is a slant top with single CD and radio. On far right looking at rear of unit is giant multiplug with I am guessing speaker outs and DC in. On left side near antenna is smaller plug with lighter gauge wire and next to it an empty plug altogether. Hoping the line level pre out is on here somewhere? Found this pic on web that looks exactly like unit in my car.

[sly]

The "subwoofer" plug has line outs on it. It's the same 98+. The fun part will be finding a connector to plug in and modify to connect to what you install. I have the pinout for that here:

[thomash85715]

Yes I had run across this chart during an eye-crossing google session that lasted hours. A place called metra has plug sets that include this I believe. Somebody on ebay has the rear woofer and amp out of a town car but mounting in my car would be complicated without some sort of intermediary bracket structure. Thank you for the confirmation though. But is the subwoofer audio output balanced? It shows + and - and shield so wondering how that will interface to aftermarket amp that is unbalanced single ended? If it is truly a mono signal, I can just dump one of the phases to ground I guess? And the image of the OEM TC amp n speaker showed a giant harness coming out the amp that I doubt exists in m car. Though there is an 8 pin plug with wires coming out the radio. Where does it go if I don't have a rear sub and amp?

[Mustang Eddie]

Moving closer to putting a powered sub in the trunk of my 08 MGM LS but hoping to extract preamp output from the factory head unit rather than use the power amp signal to the speakers. My radio is a slant top with single CD and radio. On far right looking at rear of unit is giant multiplug with I am guessing speaker outs and DC in. On left side near antenna is smaller plug with lighter gauge wire and next to it an empty plug altogether. Hoping the line level pre out is on here somewhere? Found this pic on web that looks exactly like unit in my car. [ATTACH=CONFIG]51780[/ATTACH]

Can help you out with the 2 smaller plugs if you need them.Bought a kit but only needed the big one.

[thomash85715]

Thinking about this more; I recall that there is a plug in the radio now even though there is no woofer assembly in the car. My plan might be to just slice into the pertinent wires and tap in leaving plug intact for whatever reason it is there. But Thank you Eddie for the offer if I end up needing your unused plug. Will let you know.
I do want to offer this: I have been on jaguar, BMW and Porsche forums and this is the most down to earth normal group of guys on any car forum I have been on. Thank you for being here.

[sly]

the output is mono. + and - are signal. Shielding is specifically to keep the other electrical noise of the car out of the signal and is not part of the signal. It isn't a stereo output. I have the subwoofer from a 92 touring sedan that I used in my car for a while. It's not in there right now, but in my shed as part of that sound system (pile of parts with a PC power supply for 12V).