Reply to Traktor scratch Audio 6 fit for this kind of setup ?

Hello guys !

Sorry it this might look like a silly question as I don't know much about NI gear and DVS in general.

I own a Twitch and recently acquired some nuo 5 mixer as I want to learn scratching.

I am planning on getting a turntable and Traktor Scratch next. However, I am not quite sure about which NI soundcard (audio 6 or audio 10 ) would best fit my needs. As I am only a beginner, I would like to go for the cheapest option (audio 6) if possible.

Basically, I would like to be able to mix four channels (2 "regular" decks, 1 sample/remix deck and the "scratching" deck from the TT)using only two channels on my mixer

I wondered if I could route the output of the TT through one channel of the audio 6 and the other 3 channel through the other output, using the third main "in & out" as a send return for effect ?

Basically this would mean that the "regular" and "sample/remix" decks would be mixed internally in Traktor (controlled with the twitch and maybe a F1) and that the 4th "scratching" deck would be mixed "externally" through the mixer so that I can take advantage of the eternal crossfader of the mixer.

Is this at all possible with an Audio 6 or should I settle for an Audio 10 which is much pricier ?

Many thanks for your input guys and sorry if some things are not clear as I am not a native English speaker.