Concert II Dension or Connects2 for USB Input

[Max M4X WW]

Hi all,

I'm sure this has been asked loads already, but I'm currently awaiting delivery of a factory Concert II headunit to put my car stereo back to standard. I want to then get a USB input, but which kit is best? Or is there another better one available?

I found this: Audi USB adapter interface A2 A3 A4 A6 A8 TT Concert Chorus Symphony Navigation+ | eBay

And I think there are a few Dension's available, what is the difference?

Thanks in advance!