I have played the Pa3x and to my ears the sound engine in this Pa4x is much much better(atleast 5 times as good if not 10 times ). It`s more realistic yet retains the thick sound that Korg has. I think Korg has a winner in the Pa4x and is now getting closer to the T5(but still some distance to go). IMHO, almost all the sounds and styles in the demos posted on the soundcloud are quite lively and realistic. Good one from Korg !!