zynjacku is JACK based, GTK (2.x) host for LV2 synths. It has one JACK
MIDI input port (routed to all hosted synths) and one (two for stereo
synths) JACK audio output port per plugin. Such design provides
multi-timbral sound by running several synth plugins.

zynjacku is a nunchaku weapon for JACK audio synthesis. You have solid
parts for synthesis itself and you have flexible part that allows
synthesis to suit your needs.

lv2rack is a host for LV2 effect plugins.

http://home.gna.org/zynjacku/