Hi Geoff,
I own aLuipo, but we do have the same antenna. I don't have an empeg, but I'm not too happy about that antenna VW puts on our cars. While it's okay if you have an original VW HeadUnit, it just doesn't work well even with Blaupunkts, at least on my two Lupo's I've owned; and before someone asks: I used the adapter...so what I'm trying to say (in my not-so-good english..) is that I?m going to change the antenna for a non-VW one, one that has a normal lead coming out where you have to connect 12v + . Maybe this could "solve" your AM problem? But it's probably not an easy job to change the antenna in a Golf; as it's not quite easy on a Lupo.