Charlie, It is a most confusing thing. I just had to look in the player, being convinced that I had it off for months - by accident (I just don't pay attention much I guess). But I have it on (thus for months).
I remember reading that PE must be used with AP right now (.9z-6-1c), else PE does nothing.
True. I don't know abuout 0.9z-6 anymore, but here it is so that you can't engage it without AP. Should be the same in 0.9z-6.
PE On "creates" distortion in very high frequencies and this is by accident (I call it a compiler bug because I can't find anything else). It should reflect very high transients which with Off would be better (more transient). Otoh, the frequencies involved are too high to be rendered well by an audio chain, so when a very steep transient is there (which theoretically is up to inifinity for (sine) frequency) it might be better to "round" that by means of the distortion occurring. This is why it won't work out the same for everybody but also it will differ per other settings influencing a better sound reproduction. And at writing this I suddenly see the logic of that really, because I have these new settings all engaged and that *really* matters.
If you read the above again, you will (still) appreciate it as balony because it is tough to explain distortion for the better. But I really have less distortion in general which is very audible *and* I have PE on, thus that by itself distorting. But it may need it (the rounding) or otherwise (my) speakers can't cope (?).
It was only yesterday that overhere we were talking outloud about that it doesn't need to get better because all just plays without any anomalies or disturbances. It seems it can't get better.
And PE is on. So ...
Peter