all the connections seem fine. in fact, i quite clearly hear static, so i'm wondering if it's an audi specfic problem. i swear it worked at first, for about 1 day.
anyway, i now know that audi uses a 'diversity' antenna system - there are 2 plugs on the back of the original unit and apparently one goes to the front of the car and one goes to the back...so i'm researching where to go from here.
any advice would be appreciated!