If this is all true, and you all will be perceiving 0.9z-4 the same as I do, I really will have a problem. It will mean that I must start to apply illogical things to make the sound better again. My quest for the 1:1 has been reached and now turns out to be wrong, and now I'll have to find a way back. I don't think I will be able to.
Here is where digitally tampering the sound does come handy to make more pleasant what horrors have been registered in the CD.
AP does a great job but sooner or later i was afraid that it wouldnt be enough. I'm not by principle against applying some filters in REVERSE mode of what has been done to the signal at the beginning (compression, but not just that), but I know that you were.
But I think that it has to be left to the end user what and where to adjust (i.e. as simply as a treeble DEboost), because in truth is album-based.
I'm also afraid that when all albums sounds great, there IS second harmonic added, be it by the OS, the player, or another part of the chain (that latter is ruled out in your system).
For the records, I use z2 with my studio PC, where i have a pretty bad OS dac and it does sound easier to my ears than z3, and it's more responsive, which i NEED when i'm working at the same time.
Lastly, remember the priority thing about W7? Maybe it is JUST THAT the cause of unpredictable SQ from one day to the other?
Or they fixed it in the SP1 (which will be retail 2-3 weeks btw)