This is a quick & dirty way to attach an Akai MPK mini 2 USB MIDI controller to Linux so the Linux machine can act as its synthesizer. This approach should work for any modern USB MIDI instrument.
I looked around on the web and, surprisingly, I didn't find any simple options for quickly starting Fluidsynth up and wiring it to a MIDI controller for simple keyboard usage. There are a few out there that involve using Qsynth which is cool but I didn't want a GUI for something relatively simple.