Guys Yamaha tried something very close to this around 1996. It was called the QS-300. Of course the public wasn't ready for it then, but I think with all the positive reviews arrangers have been getting, the time is right to make one.

Squeak
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.