Hi Leo,

I'm at the low end of the PR group with the PR54. However, having owned a KN6000 I'm at least familar with much of the things it and the KN7000 can do and less so with the PR family of instruments but I too will be happy to try to answer a question if possible. I don't know where the PR604 stands from a compatibily stand point but I've been happy to find the PR54 is able to read and play things from the KN6000/6500/7000 keyboards. Although so far it doesn't go the other way.

Heather