I know all this work, but again, it does not result in a common agreed measurement setup. ............
So which curve describes the sound characteristics by its own? Answer: none!
My own measurements help me to correlate what I hear, by making a correlation to the relative shortage or excess in certain frequency ranges. That and only that was the purpose of my exercise.
I commend your efforts, obviously folks are working on some grand method to correlate observations with what we are hearing…..the graphs get thrown around but they are far from telling the whole story.
What I find most despairing in these forums, hobbies is that with the thousands of users we are sort of still left in the dark with how something may or should sound, we gather a general inclination of what to expect by familiarizing ourselves with specific reviewers, even if we agree or disagree with their findings but at least we have “some sort of references”, which I see is exactly what you are proceeding to do, so kudos.
Without having to force ourselves with trying to read between the lines it would be nice to have some direct feedback on these forums from the manufacturer on their development and goals pertaining to a new product.
This especially holds true for an offering, which has been heralded to maybe replace a company’s stalwart (s), in this case the long standing 600/650s. The HD700 IMHO was a break through in development but too much a departure for those enamored with an older design and its (sound) comfort factor. It’ll be 50 years since Sennheiser released their first open back headphone and I picked up my first pair of HD414 not too long after but after all this time sometimes I get the impression that even Sennheiser and many other long standing manufactures, AKG etc., keep on re-inventing the wheel…. seriously …with decades of R&R… some one, somewhere must have an inkling of what it takes to develop a neutral emanating transducer (my preference) that we can all sort of agree on being such (not speaking of personal preferences)...and not for thousands of dollars…or is that we can never agree on what it is due to personnel preferences and lack of some accepted standard and method of measurement.
I’m just a layman on the sidelines but I still hold some hope for the 660s, mixed reviews are always to be expected (we may even have Tyll’s before the weekend) and I’ll give my 2 cents worth, if and when they ever arrive, lol…
With hundreds of different sounding headphones to choose from today, I’m far from expecting neither something perfect nor hopefully something to replace them but at least the 660s should be a refreshing update tonally of the "tried and true" but somewhat IMHO the long in tooth 600/650s …that is if the R&R department have not been sleeping these last few decades…... : (