With an elektron box as master and a keystep you could probably just use a RK006 and be done with it. If you use the keystep as input device on the elektron, just connect the keystep out to elektron in and rk006 to elektron out. Then you can connect 10 midi devices to the RK006 straight away and without timing hassles. It is also possible to merge the keystep and the elektron on the RK006 if you want to use both as independent sequencer sources. If you have some midi machines with a hardware thru port you can also use that later in the chain to expand to even more devices, but generally it is best not to go daisy chaining midi devices.
