This device can turn your semi modular mono synth into a 4 voice poly synth! Bought from Space Brain Circuits (Chicago) a year or so back. I used it for a while with the moog grandmother and it is pretty special hearing it in 4 voice and duophonic mode! Some info from Space Brain Circuits: The MidiVolts Desktop is a MIDI based 5 octave CV controller. The device contains 4 separate CV outputs with an associated Gate output. These CV outputs are called voices, and are named V0, V1, V2, V3. Each voice operates on the 1 volt per octave standard for eurorack and most hardware synthesizers. The device uses 6 different modes (MONO, DUO, UNISON, POLY3, POLY4, CC) to control each voice in different ways. See below for descriptions of each Mode. The device also contains a Midi to Clock output conversion and further customizations with SysEx midi messaging. This version comes with an added USB mini port that allows changing/ upgrading the firmware, which includes Midivolts Split firmware. This allows for different Midi channels to control the various CV outputs independently.