Again, here am I. Good new and bad new: thanks to the
self-calibration routine, You wisely suggested me, I finally noticed
that the six voices sounds perfectly, with my satisfaction in
listening lots of superb presets, so I think all the CEMs are OK,
but....still I hear some strange behaviours on about 1/4 of the
presets, that could be summarized as followed:

1) On some of the misfunctioning presets, the sound becomes thinner,
something like "less chorus", on the last, let's say, two octaves.

2) On other ones it seems one oscillator resets its envelope, from the
central part of the keyboard to left, more and more as I play higher
notes, until one oscillator "disappears" with a progressive delay on
the attack portion and an apparent resetting of the other values to zero.

3) On the rest, the sound disappears at all on the last octaves.

I made a reset after the calibration, so I think there is nothing
more to try....Well now I think It's something else but the CEMs,
maybe the OS or, my humble opinion, worn presets memory battery...What
do You think about

And I also beg You to report any error of mines in writing, just to
allow me improving my English and let me explain myself better as a
sign of respect to You all,

Thanks a lot again, and cheers!

Francesco.