I just bought a Casio CT X-5000 last week and if it wasn't for what I had learned with my music studio setup with lots of MICs I might still be looking for a solution for a keyboard that wasn't responsive to anything I plugged into the mic input. Cutting to the chase all you need is a preamp. My Berringer U-Phoria UMC404HD interface uses an additional 48 volts as will as my InnoGear 18 volt mic booster. Yes, Casio could have included a special mic plus the additional preamp but it might have raised the price. I solvrd the problem in just a few hours, not to mention a 157 page manual. Anyway enjoy our new fun tech toy. I plan to keep this amazing instrument for a long long time.