Replace Concert Head Unit - Questions ?

[JoA8D2]

Hello All, I am looking for some expert advice on replacing my Concert head unit
in 1999 D2 (pics of the connections below) I have Bose speakers and amp under CD changer.

It looks to me like the line out off the Concert head unit sends to the amp and then out to speakers, would that be right?
Is it not worth getting started with or double ? I have previous experience as mobile phone/ICE installer (many years ago) so should be ok re-wiring if needed.
Thanks for any help