First of all, I have to apologize some to George Kaye who mentioned that one of the advantages of Yamaha's plug-in slots is the added polyphony. I felt that was not an important advantage, as I would add cards with one or five additional notes of polyphony. However, for those that emphasize piano sounds, a piano card plug-in would add 64 notes of polyphony for the piano sound alone. This might overcome the polyphony problem for the PSR9000Pro only.