I recently had a chance to hear Jan Punter’s Wren during the 2018 electro-music.com spring equinox streaming radio concert. This synth is amazing. It produced a vast range of sounds, from bongo-like percussion to deeply disturbing growls to mellow flute-like breezes. He offers it under a GNU license, so if anyone wants to nab the source and make it ready to compile on Linux, I think a lot of us here in the Linux audio world would welcome that.
Great stuff, Jan!
Check it out here: http://bluehell.electro-music.com/wren/
It may work under Wine if anyone wants to try, but not sure JACK will be able to reach it that way.