Floating around on the internet are demo tracks for the Roland SC-88, with names Y4002_0x.MID (x <- {1..7}). Most of these files have more than 16 parts, requiring the simultaneous use of 2 MIDI ports. However, the files contain no "MIDI Port" or "Device Name" events to direct players to split the load. Since aplaymidi supports the "MIDI Port" event, this script prepends every "PartB" track in the input file with one, and saves the resulting file as <infile>-split.MID.

E.g. to play Y4002_02.MID ("Myth" (C) 1994 Roland Corporation):

$ ./split_channels.py Y4002_02.MID
$ aplaymidi -p<1st_port>,<2nd_port> Y4002_02-split.MID