I have a 98 A4 with a non bose stereo and am wondering how I could wire up a 10" sub to the stock amp on the rear speaker,is it possible or do I need to get another amp and connect that to the stock amp,how would i do that . any input will be helpful thanks.

 

i would not recommend hooking up a sub to your stock amp, the stock amps are pretty low power and are meant for door speakers. if you did end up hookin up the sub to it you would probable just fry the amp anyways by drawing too much power at too low of an impedance

 

simple answer: no
complex answer: stock amps are made to handle those tiny *** subs they put in. theyre only like 4-5 inches in diameter and dont take much power. the stock amp doesnt produce much power either, plus its tuned to use those speakers in the stock enclosure. if u start changing stuff, but not all of it, itll end up sounding off and just plain weird. i dont like the factory setup for its crossovers(if any at all), the stock EQ doesnt do much and its very rough. you may also blow that amp due to different impedance of the aftermarket sub vs the stock subs.