Hi Jude. Very interesting indeed. Not trying to disagree with your findings or anything, and definitely not defend Tyll Hertsens or anyone else, for that matter, but several other people, as well as other publications, (besides Innerfidelity), have measured significantly higher harmonic distortion in the bass below 80 hz on the HD800S compared to the HD800. And this is with both headphones available to measure back to back. Why would this be? I personally find the HD800S to sound just a slight touch muddier and less distinct in the bass compared to my regular HD800, especially when listening to bass heavy music, plus my regular HD800 takes equalizing (boosting) the bass, better than the HD800S, which becomes even more muddy with low bass boost, compared to regular HD800... Just sayin.