Due to its clever, detailed sound programming, GeneralUser GS can sound as good or better than SoundFonts that are 2-3 times its size.
GeneralUser GS requires a SoundFont synth with support for SoundFont 2.01 modulators.
Compatible synths include FluidSynth 1.0.9 or later (and other software that uses FluidSynth such as Qsynth, LMMS, and ScummVM, just to name a few), MuseScore 2.0.3 or later, SynthFont2 220.127.116.11 or later, and VSTSynthFont 1.080 or later.
You can select the active SoundFont in Haiku's Media preferences.
For the mapping of the percussion instruments, see the 'documentation' folder.