Evaluating the piano samples thru a pair of Sony studio headphones, I feel the Tyros, though lacking the extra deep rich bass of the 9000pro & 9000pro Exp board, has a better overall pleasing (unfatiguing) sound, especially in the mid & upper octaves: spacious & clean, with clarity & detail.

The 9000pro and 9000pro Expansion board provide a fuller sounding bass, but as a result the 'over all' sound seems a tad bit covered (muddy?), and the mid-upper octave notes (and chords) sound harsh, almost as if the notes were plucked, the 9000pro more so than the Expansion board.

For an 76 or 88 note solo piano playing situation, I'd probably choose the 9000pro expansion board for its rich full bass, but for 'piano' comping & soloing in arranger keyboard mode, I give the Tyros the edge.

1) Tyros, 2) Expansion Board, 3) 9000pro

- Scott