I have a McMillen 12 Step and when I have used it to control my Sirin in the past, I used the McMillen MIDI expander to go in to the DIN MIDI connector on the Sirin. But then it occurred to me - can’t I go direct from the USB MIDI port of the 12 Step into the USB MIDI port of the Sirin?
It seemed to good to be true - the 12 Step manual says that in order to control MIDI hardware you need to use the expander box - but maybe I’m wrong?
Sorry that I am a MIDIot!
Sorry, I don’t have the answer but I loved the MIDIdiot pun 
That being said, I would try myself. You can also contact KMI directly.
Thanks stiiiiiiive - after looking at manuals, I don’t think it’s going to work. I think I knew this - is this a symptom of getting old? 
I thought of the MIDIot thing because when I was an 11 year old kid in 1982, a new magazine came out, called Vidiot, with The Beatles on the cover for some reason. I was really into The Beatles, having just discovered pop & rock music after moving to Japan because of my dad’s work. That has stuck in my head this past 40 years and popped out now!
