Don't think that technisat unit will work because....
This is the connection diagram for fitting the technisat unit to the dresden-navi unit.
note the pin layout.
and this is the layout on the back of our headunits
(thanks to andy15star for the photos)
The likely connection block for the aux-in/usb/etc is the blue block i reckon. so whatever aftermarket solution is, will need to plug in there.
This is the connection diagram for fitting the technisat unit to the dresden-navi unit.

note the pin layout.
and this is the layout on the back of our headunits


(thanks to andy15star for the photos)
The likely connection block for the aux-in/usb/etc is the blue block i reckon. so whatever aftermarket solution is, will need to plug in there.