the reason you don't like the piano when on fixed velocity is because when the velocity is on you are hearing the filters open and close with different levels of touch. When you turn this off, the filter are wide open at their brightest. This would not be a desirable way to play your PSR1000, or any other piano in any of the newer keyboards. Back some time ago, only the volume changed when you used velocity, but today, the tone and dynamics of harmonics are affected with touch sensitivity. That why so many electric pianos sound so much better today.
George Kaye
Kaye's Music Scene
Reseda, California