Playing MIDI Files on the Modern Mac

Apple has nearly gutted the ability to simply perform MIDI files. It was once a natural element of a web page. Now it is not automatic and the volume is only a whisper.

There is a fairly good way to play MIDI files; it is not simple but it is flexible. In the application Garage Band open an old ‘project’ or create a new one. 

Launch Garage Band.
Click “New Project” in left of window.
Provide a file name (which you will not need to remember except to erase sometime).
Show MIDI file in Finder.
Select MIDI file.
Type Command-C. (or Menu > Edit > Copy ...)
Click in large gray area of Garage Band Window.
Type control-V.
(One green bar per MIDI track should appear.)
Click right pointing triangle at bottom of screen.
You will probably want to click the metronome icon to suppress its sound. Now you will hear the music played by the “Pop Flute”. That is not bad but if you want to hear it by some other instrument you must change each track; you may select different instruments for different tracks: 
Select a track by clicking at left of window.
Type splat I
Select instrument category in left of window pane on right.
Select instrument in right of window pane on right.
The name of that instrument should show in the left of the window opposite the track.

I think the tempo is wrong. There are drop-outs every few minutes—a fraction of a second.