Reply to My Studio/DJ Setup

Hi guys, I am collecting money to get a good setup. I was believeing of getting these items:

Monitors:
2*KRK RP5 G2SE

Midi Keyboard:
M-audio Axiom 25 ADV

Headphones:
HDJ-500

Audio Interface:
Komplete Audio 6
OR
Scarlett 2i4

Mixer:
Numark mixtrack pro(already have)

The biggest problem is with the audio interface, I don't know which one to pick. The difference that I see between them is that the Audio 6 has all balanced in and outs and a SPDIF(which I believe that I don't need). The Scarlett has both balanced and unbalanced(I believe that I need the unbalanced because if I go to my friends they don't have monitors so I have to plug a set of 2.1 speakers for djing). But when i was looking at some pics I saw that they don't have a place where you can plug inputs. I want the inputs because I would like to use the interface for both producing and djing. As I said I have a Mixtrack pro and the outputs are unbalanced. Is there a way in which I can run the audio from the mixer to the monitors using an audio interface or do I need to get a better mixer with unbalaced?