Thanks for posting about this. I've been thinking of getting the HD800S as a counterpoint to my LCD4s: the latter are warm with emphasis on mids and bass, whereas I've read that the Senn's emphasize the treble and are known for their detail and imaging. And whereas the 800 (not the "S") was reported to be a little sharp at 6KHz, I've read that this is now fixed with a "resonator" donut that counteracts the 6KHz resonance.
And now there's the HD8XX! Going by the ad copy on Drop, it seems it uses the same drivers as the H800S but with different damping materials and a different resonator donut. The frequency response plot comparing HD8XX to the HD800S looks promising. I like mids and bass, and so the HD8XX may be more up my alley. But the plot showalso s that the 8XX has an even greater boosted response between about 2.5KHz and 4KHz. I've read that 2K to 4K is the range of the human voice, but also chalkboard and styrofoam squeak, to which I am unusually sensitive.
Before reading your post I was pretty close to pulling the trigger on the HD800S. But now I'll wait to read some non-Drop reviews comparing the HD8XX and HD800S before choosing between them.
cheers, Derek