next upgrade/ piece of gear?
current gear: Numark Mixtrack (Soon to upgrade to a Kontrol S2), Midi Fighter Classic, MDR V700 Sony Headphones, and my laptop 
so what should i upgrade after my mixer? or should i get something like a Midi Fighter Pro? Suggestions plz?
ps- btw there are three of us together who DJ at the same time 
(think above and beyond)
i don’t know what sort of controllers your friends have but if the al have midi ports on there controllers you could sync your devices (i’m not shure), if you buy a S4. i would not buy a MFP, maybe somthing like a launchpad, X1 (or one of those berhinger controllers), maybe even a oxygen 8. It depends completly on your needs. If you realized after reading this, i don’t need any new stuff, then i would take a look at a pair of Technic’s