QSynth is a Fluidsynth GUI front-end application written in C++ around the Qt3 toolkit using Qt Designer. Eventually it may evolve into a softsynth management application allowing the user to control and manage a variety of command line softsynth but for the moment it wraps the excellent FluidSynth. FluidSynth is a command line software synthesiser based on the Soundfont specification.
Download it here.
It could be useful to use soundfonts if you do not have a Soundblaster card. See Section 188.8.131.52.
$ ./configure --prefix=/usr $ make $ su -c "make install"