I have 2x SC6000’s + DJM-900 and I’m wondering how I might add some new effects to play with during a live performance?
I’ve looked at RMX-1000 and Kaoss Pad but they have been around for a while now and perhaps there are better options using Ableton Link?
Check the NEW SP-404 mk2 from Boss/Roland Or RC505 mk2 - I just received one yesterday - great looper/effects processor.
I don’t think there’s any effector with Abelton link yet.
However if you have an interface for your phone that let’s you run midi cables or a laptop then that’s the only way to sync to them for now.
The mk2 loopstation is a good all-arounder. I have the mk1 and I’m waiting for the mk2. If you want just hq effects alone then check the Line6 Helix.
Akai force, akai MPC One - you can set inputs to directly run to output thru an effect maybe? They have Ableton link. But also if You run any Ableton link device with midi out, You can sync that together.
This looks like more my style, I’ve seen what Marc Rebillet can do with one. However, it does not seem to have Ableton Link, so can it take a clean 4 or 8 beat sample that will stay in time with the source track?
I bought it to exactly that purpose, but I will sync it via MIDI. I will check this weekend how stable tempo is and if it can be synced easily.
I have my loopstation connected to my iPhone via midi cables and use an app called link to midi.
It’s stable and works very well but there’s an offset when changing tempo but it catches up quickly. Once you get the settings dialled in you’ll be happy.
One thing I have to mention though is that the 900nxs2 is not really setup well for taking full advantage of external effectors and samplers. You’re most likely to get phasing issues and also feedback issues.
Wash your mouth out…ahh I mean why!? It has the send/return stuff. 
Mixers that have fx sends on the channel strips are perfect for live sampling and external effectors.
Mixers with fx assignment as a knob off to the side are not ideal. You will have to perform a ritual every time you want to use your external unit.
I you look at my mixer the dn-x600 you will see that fx sends switches are on the inputs ready to turn ‘on and off’. On your pioneer or a denon x18xx, when you assign with the knob you’re stuck on that channel with no way to turn the signal off. It is continuously on.
Mixers like Allen and Heath have the fx sends on channel strips. That’s why people who want to plug in externals buy those mixers.
Just a note on the XONE96 (I own one), the EFX insert is on the master out ONLY and you would need a external soundcard if you are streaming or use the the master out only for recording, not the internal USB sound cards. It does not route the master EFX insert to the USB audio card(s) and if you are thinking of using a RMX-1000 (own that too) with the XONE96 and using the send/return fader there is a a slight delay causing “phasing” due to the RMX-1000 audio processing delay of about 50ms.
You would know better than me of course because you own it. Maybe show a diagram of how you have you external effector hooked up so we can all learn.
What I see on the 96 are 2x sends on the channel strips with a pre switch and I see the return for those on channels a+b which looks good for standalone use.
I have a video showing how I do it on mine. Maybe I’ll post it.
It seems like the mixer manufacturers have not figured out how to create a common standard for plugging in external effects units. I mean it’s not like they play well together anyway but yeah. 
I like the Mastersounds solution I’m running but that would involve getting rid of the Pioneer and buying a new mixer 
The mix bus is great once you get used to it, and the non Quantized FX can be interesting to work with too.
Some of Strymon’s guitar pedals run fine on both send/return and insert type effects loops. I have the Nightsky (reverb) and the Volante (delay/echo) . Both work with either effects loop. The Volante can also be tempo-synced via midi clock - just run a 5 pin midi cable from the midi out on the mixer into the midi in on the Volante.
Another option would be routing the audio through a DAW. I use Maschine to achieve that. I’m not familiar with the DJM-900 USB audio routing, so that solution might involve an additional audio interface.