Both the D-50 and D-550 benefit from the PG-1000 external controller which gives you very plain and simple slider/fader type control of all adjustable parameters of the synth. The D-50 includes MIDI on all 16 channels but because it is monotimbral you can only use one channel at a time. There is an upgrade which will give the D-50 and its rackmount version a full 16 channels of simultaneous MIDI multitimbral data communication. This popular synth has been widely used in all forms of music. Eric Clapton, Enya, 808 State, Jean Michel Jarre, Vince Clarke, Apollo 440, Eat Static, LTJ Bukem, Fluke, Information Society, Lab-4, Gary Numan, Rick Wakeman, Kitaro, Rush, Vangelis, Richard Barbieri, Boston and Nick Rhodes of Duran Duran are just a few of the many satisfied users.