After testing the three pedal inputs of the Korg Kronos with the Roland DP-10 I assumed that the Roland RPU-3 pedalblock will do a perfect job as a foot controller. I connected it to the three pedal inputs (damper, switch, and pedal).
Sustain alone works great. However, the three pedals and their plugs do not work independently. Instead, they influence each other. For instance, when assigning the left pedal to an oscillator’s pitch, all three pedals affect the oscillator’s frequency, surprisingly at different amounts of about a minor third, a fith, and a minor seventh. But pressing all pedals simultaneously will not result in a pitch shift which is about the sum of all those intervals.
To make it short, the Roland RPU-3 can’t be used with the Korg Kronos meaningfully. In case you can share some pointer to an alternative pedal block or to some instructions how to modify the RPU-3, please do not hesitate to drop me a line.