Mac,
Yes, I drive the PSR2000 with a Casio Wk-1800 which is 76 keys. I assume you could use any 76 key midi keyboard to do this. The PSR has great midi settings and allows all kinds of configurations for that purpose. My daughter has the same setup. Works great!
-Linda
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Linda F
Casio Privia PX-560 - Korg Micro Arranger - Casio MZ X500