Reply to Kontrol S2 W/ Pioneer DJM Mixer

I've tried to find a thread related to this but instead ended up confusing myself with situations that sound similar to this but aren't.

If I wanted to use my S2 (instead of CDJs) with an external mixer such as a DJM-850 would I need to purchase an additional soundcard (Traktor Audio X, etc.) to make this work?

Appreciate any responses.