Technical Rear Speaker wires (non coachbuilder option)

[eggy43]

I've got a 2019 (68 plate) Ducato without the coachbuilder socket in the B pillar and want to connect some rear speakers.

I've pulled the radio out and confirmed that the connector is wired for all 4 speakers.

Does anyone know where the speaker wires go to?

 

[eggy43]

Update:
Found the connector - 10 way, passenger footwell (see photo)

Next question, does anyone know how to access the hidden menu to activate the rear speakers? There's plenty of info about the 'Nav' version radio but not the poverty spec that I have.