DJM-900NXS2 setting up digital audio (no RCA)

Hey all,

I have a DJM-900NXS2 mixer. and two CDJ-2000NXS2 players. I've performed in clubs where these three pieces of hardware were connected for digital audio (no RCA cables). I currently have all three pieces of hardware linked via an ethernet switch and I run RCA cables to the mixer from the two players, but I'm interested in using a digital audio link without the RCA cables. I can't seem to find a tutorial on how to do this anywhere - could someone help me out with an article or youtube video?

Thanks!