There is no "correct" sound for a MIDI file
In the case of canyon.mid there is because it was composed for a specific midi instrument with a particular set of timbres.
Or to put it another way, it’s music and therefore complicated.
I think the OP was referring to the difference in synthesizers. It sounds a heck of a lot different on an MT-32 compared to a Sound Blaster: https://youtu.be/0j4uywdNq44
I can play the guitar parts on a banjo but it ain't going to sound right.
In 1900, QRS began making piano rolls. By 1920, they had invented a machine to capture piano players directly and over the years QRS captured many including Liberace, George Gershwin, and even Roger Miller playing Autumn Leaves.
QRS is still in business and some of its product lines use Midi conversions of piano rolls and last month I landed a mixed lot with a bunch of those Midi files on 3.5” floppy disks.
I had George Gershwin rocking a Yamaha XG clavichord and Liberace on a Sitar and similar shenanigans.
It was composed for at least two, the Windows 3.1 version uses Microsoft's weird MIDI format from that time that contains a simplified version of the arrangement alongside the full version, and which you would hear depends on the configured MIDI Mapper settings.