Revo DAB Adaptor

Looks impressive but do you really want that cheap looking box cluttering up the dash with associated wires all over the place, when you seem so concerned about changing the look of the existing head unit?
Also it would only work via the antenna input method as the only Aux input on Audi HU's is via CD changer input, which you then have to fool the HU into thinking it has a CD changer connected, so you'd need to buy some more hardware to do this.
Connecting it via antenna will mean you won't get the additional sound quality that DAB offers, but I guess if you're happy with the SQ of the OEM system then this wouldn't be a big concern.

It's certainly a cheap alternative to a dedicated DAB HU or DAB ready HU with separate receiver. But it's a bit like connecting your discman to your car HiFi via a tape adapter.