The Yamaha KX88 is a MIDI controller used by Prince and other musicians from the mid 1980s onwards. A KX88 was mounted inside a fake piano shell and used to control a Roland MKS-20 sound module.
Prince played a Yamaha CP-80 on the 1999 and Purple Rain tours. A problem with the CP-80 was that Prince liked to dance on the piano, causing the strings inside to vibrate. For the Parade tour, Dr Fink had a KX88 mounted inside a dummy piano shell, controlling a Roland MKS-20. Prince apparently couldn't tell the difference between this setup and the real thing. This "piano" was played by Prince, Lisa Coleman, Boni Boyer and Rosie Gaines.
Dr Fink also had a couple of KX88s in his rig, and used it to control a Roland D-550, MKS-20 and other sound modules. These controllers were also used by Tommy Barbarella when he joined the NPG.
About three years ago, we had a real Yamaha grand [CP-80]. We put Barcus-Berrys and other pick-ups in there. They sounded okay, but they picked up a lot of ambient noise. And Prince used to get up on the piano and dance, so forget that. Anyway, the sound man came to me, because he didn't want to bug Prince, and said, "Matt, I got this problem with the sound in the piano. What do you think we can do?" I said, "There's this new MKS-20 thing. I think we should try that out, and put the Forte MIDI mod in the piano." So we put that in to trigger the MKS-20. I tried it out, and it sounded really good. Prince showed up for rehearsal a couple of days later. He had no idea that we had modified anything in the piano. He sat down at the piano and started playing, not saying anything. I walked over to him and said, "So what do you think of your piano sounds" He said, "Sounds really great! What did you do?" I told him what we had done because of the ambient noise problem. He said, "Wow! Good idea. Thanks a lot." The following year, the crew people came up and said, "We can't haul this big Yamaha grand around anymore. Besides, it's totally useless, since you don't even need the soundboard anymore." So I said, "Why don't you have a fake piano shell built, and mount a [Yamaha] KX88 in it?" That’s what they did, and they strengthened the top so that Prince could get up and do his stuff on top of it.