The only thing I don’t think works is looping back on MT1 Out back to MT1 in. For that I would use something like MIDILoop or MID Yoke (if on Windows). I think I ran into this as an issue before if you are trying to process the additional input coming back from MT1.
I think Mac has a native way to create and use virtual MIDI ports.
Hi, just a quick addition: you can use the Bome virtual MIDI ports generally in both directions, also for a loopback — on Windows and also on Mac.
Just make sure to not create an infinite loop — e.g. if your DAW is set to MIDI Thru/Echo (MT Virtual 1 IN to MT Virtual 2), then connecting Virtual 1 IN to Virtual 1 OUT in MT Pro will create an infinite loop, which can slow down your system considerably…