zynjacku (LV2 synth host, includes lv2rack)

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.

lv2rack is a host for LV2 effect plugins (like jack-rack is for LADSPA
plugins).

This package requires jack-audio-connection-kit, lv2, slv2, and
lv2dynparam1 (all available at SlackBuilds.org).

lash is also recommended, though not required.