I had a Kn5000 and have a KN7000 now. I would not recommend for master controller of Audya4.

If anything, Audya4 has had more problems( at least before the updates) than the Audya5 and 76. I also have an Audya76 with no problems whatsoever.

The Audya5 has 61 keys and the Audya76 has 76, not sure about the controller difference.

In my opinion, the Audya76 is the best sounding keyboard in terms of live sound. Of coarse, this is subjective.

I have had Yamaha's (not Tyros), and they are excellent boards with all the styles you could want, and very dependable as a whole.

The Audya is a work in progress from a small company. The reason I chose Audya is the sound and features, but gambled on not getting a flawed board.

For me, the Yamaha is good but the overall sound is too vanilla but some of the solo instruments are great.

Bernie