I couldn't hear any difference either. Sounded the same on both models to me. I just don't really care for the high and low register on the PSR piano samples. They're not bad, but I think this is where the sample is weak.

Squeak
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.