Lee,
On Casio keybaords, including the inexpensive WK200 and WK500 you can do what you would like the Ketron to do. Play a sound, hold the notes down, switch to another sound and until you release your fingers you don't hear the new sound or any of the effects change until you release. I also tried this on a Roland Juno Di and as soon as you select a new sound, even while holding down the keys, the sound changes immediately.
I then tried it on a Roland EXR46oriental and the sound stays until you release but the effects and preset volumes change even though you are still hearing the original sound.
On a Yamaha Tyros3 the sound stays but the effects, volume and EQ paramaters change while you are still holding the same keys down but the sound doesn't change until you release.


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George Kaye
Kaye's Music Scene
Reseda, California
818-881-5566
www.kayesmusicscene.com