Official comment
Whether you use a booth monitor doesn't matter - all it's doing is providing you another version of the master output with a separate volume control. Let's ignore that and just focus on the headphone monitoring.
You are correct in that the XDJ-RX does not feature split-cueing, it only has a stereo-overlay option. What you do have is a cue / master mix knob, allowing you to preview only whatever is selected on the channel PFL (pre-fader listen) cueing, only the master, or any amount of mix between the two.
There are two buttons below the headphone controls allowing you to select CH1, CH2, or both simultaneously - these are what you'll hear on the CUE side of the cue / master.
I typically leave mine in the middle, allowing me to hear the master output - then I'll find a new song, engage the CH1 or CH2 button (for whichever deck is NOT going to the master), then, if I need to, turn the mix to the CUE side so I don't hear the master so I can better preview the new song. When I'm ready to start the actual mix, I'll dial the knob back to the middle and toggle the channel button on and off as needed until both tracks are "live," at which point I'll usually listen to only the master - but no need to turn it to the master side, as you'll only be hearing that and nothing additional from the PFL cue.
