Make sure you have the latest firmware installed on the CTS500 and in Settings change "midi in 1-5Ch Port" from "C" to "A". (It is added in the latest firmware) ver. 1.06 I control my CTS500 with a Kawai ES920 and really enjoy having access to the additional sounds and also blending with the great sounds on the Kawai. I am using a Doremidi UMH-21 host box with a midi din cable to the Kawai and an USB cable to the CTS500. I like being able to set up tones manually on the Casio via the knobs, selector wheel and saved registrations instead of using midi change program commands.