Could i add an XDJ-700 to my XDJ-RX2 to make it a 3 channel mixer?

Does this mean that I won’t be able to hear the track and beat match it before bringing the song in?

Are you saying then that I could plug it into the aux in the back of my all in one controller to use it as a third deck?

I need to know whether I’d need another mixer or whether I could select the aux input whilst still keeping the 2nd deck input and use the mixer built into the XDJ-RX2 as a mixer for the 3rd deck.

Using the AUX input would allow you to use the 2 decks on the RX2 and have the XDJ-700 as a 3rd input source.

No, as mentioned there is no headphone cue or level indicator, so you wouldn't be able to preview, set levels, or beat-match it before mixing in via the volume knob... all it would do is give you an additional input.

Could I get another mixer and add that to the turntable to allow the headphone cue and input level?

Guess I would have to use like another pair of headphones on that specific mixer?

This might be a stupid question tbf but I do really want to add to the RX2 and feel like I’m in desperate need of another channel when mixing

Here's what I would recommend as a work-around; use the XDJ-700 as the 3rd deck within rekordbox. When you have the need to go to three sources, whatever you have playing on either deck of the RX2, you "instant doubles" over to the 700, then pull the volume up on it and kill the channel fader for the original source. If you get good enough, you should be able to do it without any seams in audio level. That deck on the RX2 is not open for you to cue with the headphones. All that without the need for another mixer.