1Simple MIDI playback with fluidsynth
Install fluidsynth and sound fonts for it (YMMV on other Linux distributions)
sudo apt-get install fluidsynth fluidsynth-soundfont-gm
fluidsynth -a alsa -m alsa_seq -g 1.0 -s /usr/share/sounds/sf2/FluidR3_GM.sf2
Check on a separate terminal for client:port numbers via aconnect and look for "4chord MIDI" input and "FLUID Synth" output
aconnect -i aconnect -o aconnect 20:0 129:0
Start playing music, that's it.
For more details, check this video: