2003 Audi A4 Avant w/ Bose

Chances are that the head unit is going to be like that of the new Mazda Bose system. Find the hidden amp and it may have 4 pairs of twisted wire coming from the head. These should be the preamp lines. If they are infact the lines it is as simple as cutting the lines away from the Bose amp on the input side, extend the wires, solder rca ends on and plug into a Audio Control EQS or 6XS. Both units have the ability to take a factory Bose input, use the built in LOC to adapt the signal, do the gain setting front to rear and then give you front / rear / sub preouts. (in the case of the 6XS it gives you remote level control on the sub).

I would dive in and see what you can find. The new LC6 is also another little gadget that can be used. Even if the factory head does have crossovers, the LC6 can derive a full range signal on the outputs. (if I heard the rep correctly)

I beleive that it is a similar piece of equipment.

www.audiocontrol.com