I find some of what you write about the HD800 S perplexing. I seem to remember that you said several times that you sold off your HD800 some time ago, so perhaps that is the basis of why some of your statements about the S vs. classic are idiosyncratic. If you read comments about the S both here and on other forums, the difference is a lot about the airiness of the classic vs. the better behaved treble of the younger bro. This is not a subtle difference. In addition, the S images a little less precisely than the classic, that difference is subtle, but still quite noticeable.
Personally, speaking, I have now tried the S on a wide variety of amps and sources. I can say that while the S, like its older sibling, is sensitive to upstream gear (though a little less so), the basic differences between them remain.
I am not trying to pick a fight, but I also respectfully and emphatically disagree with what you write here.