I tried it with Cubase and it worked, I nearly fell off my chair. But, I haven't used Cubase before and found it a strange and alien place and I didn't like the sequencer much. I'm sure it's fine, and I guess I could convert, but, I've invested quite a lot of time in Kenny Gioia's Reaper video's. Could I do that again for Cubase? I still really wanted it to work in Reaper and at least now I knew what settings would work on the SR16 for sure (Midi Ch omni, at least for now, Drum in on V1, Drum out off, Note's on the defaults, Clock in and out off, midi thru off, PRG Change On and Note Map Normal). I also knew now that the Interface and my cables work and that everything is patched correctly. So, I closed Cubase and tried Reaper again. Nothing, for about an hour, trying many of the things I had before. Really fed up. But then, I'm really not sure exactly which thing it is that I did that made the difference but now, at last, it works too. The whole setup is: Midi out enabled to my interface which has a midi cable going from it's midi out to the SR16's midi in. SR16 settings as above. Audio outs from the SR16, up to four, plugged to the interface. Add a track to Reaper and then add Reapers Sequencer "Megababy" using the FX button. Program in some beats. Using the tracks "Route" button then under Midi Hardware Output choose your interface's Midi Out (this may have been the step I was missing, but, I think I had done this before). I think I had this all in place and was still getting nothing and then chose, in the sequencers "edit" dialogue, the option to Full Recompile/Reset. I think it started working then - I'm not sure because it took me some seconds, 10 or 15 maybe to realise it was working and I'd maybe clicked a few other things by then. So in the end I'm really not sure what the thing that did it was. thanks to everyone that posted their help, in particular @rob aylestone and @vox for helping me to understand what was going on, and @spantini , for general encouragement and good humour. Mission Accomplished.