Thought I would follow up in case anyone comes looking for this info.
The non most Bose system feeds the Bose amp with a hi level input, speaker level. The amp then feeds on the rear channel to the add on amp which feeds the Bose sub and rear speakers.
Therefore no adapters needed, simply plug in the standard connectors straight into your new head unit.
The only thing you have to do I hook up the amp power on cable which is in the Yellow C Block to the amp out (blue wire) on your new head unit.
This is the new Pioneer 250Dab Car Play unit......