Reply to audio interface for 4 decks control

hey guys,

im currently running:
1 x macbook with tractor pro 2
1 x native instruments audio 2 interface
1 x behringer ddm4000
1 x traktor kontrol x1

i want four deck control because i want to buy another x1 or f1 (havnt decided yet), but my question is will a native instruments audio 6 allow me to do so? or is it only the audio 10 that allows 4 deck control?

thanks