Columbus Midi Switcher. The Diezel Columbus MIDI controller gives you full switchablity functions using external FX, such as delay and chorus or any rack FX unit with the Diezel Herbert and VH4 amplifiers. The Columbus connects via MIDI and is phantom powered from the amplifier connection. The Columbus can also be used as a stand-alone MIDI controller for any MIDI device. The rugged construction and super bright LEDs make it a must have accessory.