Yoshimi Developments.

In the experimental branch of this rather wonderful synth Cal (the lone developer) has started revising the way voice patches and banks are stored. The result is that it is now possible to change both voices and banks on the fly on one channel while other channels are continuously sounding.

Even the most complex patch changes don't make a sound, nor cause any xruns.

At present the new database format has to be loaded manually, but this is work in progress, and eventually it will be able to import and export Zyn. format voice patches.

An interesting side effect is that it is now possible to simply load up Yoshimi and have your sequencer (or other control device) specify every voice patch at the start, as you would with a hardware synth - there is no longer any need to load a patch set.

Unlike a hardware synth, you can change banks in the middle of a tune without disrupting any playing channels, and change the actual voice of one channel without disturbing the others that are playing.