Hi Rob:
WOW a PR owner. You know how that commercial goes, "PRICELESS".
I have the PR804. I would mark this forum as a favorite or bookmark it because it's a good source of Technics keyboard info. And great people too.
KN6000/6500/7000 are compatible but not at 100%. PR902,903 and their sub models also will work.
Don't forget midi files, those really sound great on the PR's.
Anthony