Reply to All-in-one board sound connections..help a rookie

So, I've searched the community s, manual, etc. and can't find this seemingly simple answer.

About to purchase a Pioneer DDJ-SX to be used with Traktor. I know the traditional setups (CDJ's -> computer -> Sound card -> mixer). Soo...do I need an an external sound card with this all in one unit? I'm hooking up my speakers via XLR. Does the single USB connection from the DDJ-SX unit suffice? (i.e., does is send info both way eliminating the need for an external sound card, or do I need one?)

Running Traktor Pro, MBPro, DDJ-SX (don't have it yet, hence the questions), and Rokits if this info matters.

Thanks guys and girls!