Thank you, I do need a bit of support.
I might have found the problem.
The main lead goes up and down, but the sublead does not follow right. I am listening at a much lower speed, which makes it much easier to pick out the bad sounding keys. And because they are in key, I was wtf ?
But some part of the sublead notes go down when the main lead goes up.
And that seems to be the part were I get the wrong shivers down my spine.
Now I will have a look at your demo first.