Reply to Traktor S2 & Audio 6

I have a question about using the S2 with scratch pro, I have been told that if I want to use the Traktor S2 with Traktor Scratch Pro I need a external sound card because I can only use the S2 as a controller in Scratch Pro and not a DVS?
I am wanting the Audio 6 so I can use it at the club with pioneer CDJ and what ever mixer there may be but I want to be able to use my S2 at home.

So can anyone explain how I would set up the S2 with the Audio 6 in Traktor?