Setup MIDI software "soundfonts mapping" (instead of hardware)

In this post, I've (quickly) explained how to set up environment to play MIDI file, loading soundfonts into wavetable of the sound card.
Nevertheless, the soundfonts which can be loaded into the sound card is obviously limited to available memory and so compromise must be done between quality and size.

Instead of this, it is possible to use software "soundfonts mapping". Today, there is lots of very powerful and mature softwares although all must be set up with caution to avoid latency issue.
There is various interesting explanations on the subject, for instance Planet CCRMA at home, and Linux MAO.

This is the software which an be used (prefixed by corresponding package name under Fedora):
- jack (Jack Audio Connection Kit): a low-latency audio server,
- qjackctl: a simple application to control the JACK sound server,
- fluidsynth: a real-time software synthesizer based on the SoundFont 2 specifications,
- qsynth: a fluidsynth GUI front-end application,
- fluid-soundfont-R3: fluid R3 soundfonts of good quality,
- rosegarden4: a professional audio and MIDI sequencer, score editor, and general purpose music composition and editing environment.

N.B.: those instructions have been performed (at least) under Fedora 8