It is a fakra connection onto the DAB module, if I remember its the black one. Fakra is basically an SMB connector with an extra housing to hold it in place.
Before I went all OEM, I was thinking of either under the parcel shelf or the top of the rear window under the trim that hides the amp.
I was looking at this one
http://www.ebay.co.uk/itm/DAB-active...item43be0fa4e2