[DannyChapman]

Thanks for the reply and explanation. From the docs, it looks like the alternative would be enumerating USB devices at runtime and requesting permission, but I assume that this is what you have tried as you say it doesn't work for older devices.

As mentioned - I am using the FluidSynth app to connect to and use the connected device using MIDI-over-USB. In that app, I have to trigger it to scan for connected devices, which works fine. It's clearly not using the intent filters, as there are no notifications relating to it if I plug in a USB device. It has basic USB permissions (I forget if it asked for permissions the first time I used it - it certainly doesn't now).

I guess, in my ideal world, MS would work in the same way as FluidSynth in this regard. I do understand, though, that there may be additional things that I'm not aware of (you mentioned the Google MIDI library)!

Thanks - Danny