Hi all, My (new to me) 2003 S4 Avant has the Concert stereo in, but also has the Bose amp and speakers - strange combo, personally if you've paid for the Bose, you'd pay for the stereo... but hey ho. My question is - can I utilise the Bose amp (therefore the speakers) if I change my Concert to an aftermarket head unit? Or are there a load of adapters etc to buy too? Admittedly, I'd like to find out now before wrecking the dash to take a quick peek! As a side thought, does the Concert allow for RCA outputs to an external amp? As mine is an Avant, the bass of the Bose sub gets lots in the vast space of the car. Thinking of sticking my external Alpine V12 amp and 10" sub in the boot (as long as it can be done subtly! - I don't drive an Astra GTE any more and don't need to show it off!!) Thanks all.