Previous command will work for the current session only. If you want to permanently add the virtual midi device (jack users on Debian/Ubuntu/Mint), edit the /etc/modules file to add snd-virmidi, and create a file /etc/modprobe.d/snd-virmidi_options.conf with the content options snd-virmidi midi_devs=1.
If you list the connected ports, you should see a new Virtual Raw Midi entry like below:
$ aconnect -lo
client 14: 'Midi Through' [type=kernel]
0 'Midi Through Port-0'
client 20: 'Virtual Raw MIDI 1-0' [type=kernel,card=1]
0 'VirMIDI 1-0'
3.
Install FluidSynth and QSynth, its graphical user interface
(tested OK on Linux Mint, if problem please consult the FluidSynth documentation)
$ sudo apt-get update -y # Get latest packages info
$ sudo apt-get install fluidsynth
$ sudo apt-get install qsynth
4.
Start QSynth
qsynth &
5.
Load the JJazzLab SoundFont and adjust FluidSynth settings
6.
Connect the virtual port to FluidSynth
You should see a new port, like in the example below:
$ aconnect -lo
client 14: 'Midi Through' [type=kernel]
0 'Midi Through Port-0'
client 20: 'Virtual Raw MIDI 1-0' [type=kernel,card=1]