u/robpoochie

I hope to replace the sequencer with an iPad for easier use. I have been looking at multiple apps to accomplish this, and am leaning towards Xequence 2. I would like to use my Arturia Keystep 37 to perform and record parts. I have the cme midi thru5 box, with 4 midi instruments connected. (Behringer Model D, Behringer Grind, Korg Volca FM, and Drumbrute Impact) How can I use the iPad to control these synths? To be exact, which cable or adapter will make this work?