I'd suggest the newer TC Helicon VoiceLive Play. Very easy to setup. You don't even need to connect it to the keyboard thru midi. You can set it up to "listen" to the music coming from your keyboard, amp, guitar, voice or any music source and it'll figure the key and provide the appropriate harmonies. It has tons of presets and other features too like looping. I'm using the VoiceLive Play GTX (with guitar effects) with my KMA or guitar and very happy with it.