Yes silvano I have had older casio keys, Korg, Roland, Technics and on all of them you can change the voicing when in layer or split mode whilst playing a song. The user registration memory on wk7600 is a good thing, but you have to remember what you have done which is impossible for 16 banks of 6 registration possibilities. I use it just for a set up of voicing, rythms etc. Incidently when in layer mode on the wk7600 you can set the main voice upper to part 2, and the sub voice to part one and alter the volume on part one to be softer, then on the display the voice is showing part 2 which you can change when playing. The problem with this though is that when you cancel the layer and set another voice which uses part one as its default the softer volume is retained, so you still have to mess about editing, again totally inefficient.