First, let me say never saw/played an SD1, but I would think that it should very do-able. The "trick" will be to understand the MIDI out functions on the SD1, and what you can/can't configure. Basically, you need the "right hand" of the SD1 to send out MIDI note info. I'm assuming you can assign a MIDI channel for that? If true, you can configure the SD40 to accept that information. The trick here is splitting up the left and right-hand parts on the SD1 and if you can configure them on sperate MIDI channels?