From the ALSA wiki
Main site: http://swami.sf.net
From the home page above: Swami (Sample Waveforms and Audio for Magical Instruments) is an instrument patch editor with plans to be much more. It currently allows editing of SoundFont files and uses iiwusynth for software synthesis, so pretty much any sound card can be used. iiwusynth gives us real time effect control and SoundFont 2.01 modulator support for controlling effects in real time with MIDI controls.