BOSE sub amp deletion/replacement?

On the A3, amp runs speakers too.

Andy Mac is the guy to speak to, hes done a lot of work with the A3, offering up a nice upgrade etc. Not sure if he does anything for A4 though.

Ive completely done away with all factory Bose stuff, running my own amps, speakers and sub, and wiring. But not tried integrating any of it into factory head unit, or existing amp .