I made a new MSDOS utility, the MIDI Sniffer:

* takes in MIDI in
* reroutes to: MIDI out, PC Speaker, or OPL2
* supports polyphony
* can take in regular keyboard playing (qwerty...] = white notes, etc)
* generate a random OPL2 instrument for you to dig and test out its values (I use that to find new interesting sounds for other projects)

it's a little rough around the edges, since it works well on my weecee but I need bug reports on other machines. it freezes in dosbox, dosbox-x and will beep with filled keyboard buffer very quickly on my 486 when you use the typing keyboard

github page including source code and .exe binary: https://github.com/Mu0n/MIDI_in_Sniffer

demonstration video is here: https://youtu.be/9_MNY7hs1qg