I've heard several people use their stock Bose head unit with a sub and amp. As for the signal, I'm not totally sure but I think that's a way you could do it. I've also seen something you can buy that goes behind your stock head unit....I'm guessing it's the same thing that you are talking about, except a different way of doing it. I went to Custom Stereo and Cellular to ask about this exact situation and this is what he told me. Hope this helps.

 

cut open some rca wires and you'll see how to make some inputs for the amp... I didn't have any money so I rigged it up... it sounds alright but there is some static noise if your amping up like mids or highs...

you could get a noise filter at bets buy or sumthing to help with the static thoe

 

I got a converter when I had my stock deck. It sounded pretty good, but don't really know how it would do if you just rigged it like that.

 

you will need:

1) x1 line output converter
2) x1 pair of rca's
3) amp insatallation kit (8 gauge kit)

you will make all the splices behind the radio for the line out converter. make sure to find a solid ground spot in the trunk and to secure the amp either to the sub box or to some plywood.

What brand amp are you goin to be using??
you can tap into the rear speaker direct but you run the risk of damaging the speaker and the radio. Thats why if you tap into the speaker wire behind the radio you put alot less strain on the radio itself. the choice is yours! you also need to find an ignition wire and or power antena wire to use as your amp turn on wire.

if you live in NY i could install it for you for $50.

Anthony