Man, I've gone down so many rabbit holes trying to figure this same thing out and on multiple forums and nobody seems to have a solid answer!
I just got a RMX-1000, and here's the best setup I've been able to figure out so far: I have Multi I/O Send -> DJS-1000 Input, DJS Output -> RMX-1000 Input, then RMX Output to Multi I/O Return. Then on Multi I/O MODE I select 1/4" Ch2/5, then on Channel 2 or 5 I select Multi I/O.
So this allows you to use the Multi I/O CH Select to select which channel you want the DJS-1000 to sample from, and then I have RCAs going from the DJS-1000 to a dedicated channel for playback.
When you turn on Multi I/O on Channel 2 or 5 you can use all the RMX FX plus EQ, Beat FX, etc.
What I haven't been able to figure out though, is if there's a way to get the DJS-1000 to sample something other than just a single channel. For example, if I have a CDJ playing a track on Channel 1 and a RMX effect going out over Ch 2 or 5, (I also have a synth on a dedicated channel) sometimes I want to sample the blended sound from all 3 devices and not just an individual channel.
If you found a better way to hook this up, can you please share? Thanks!