Hi Arnaud – nice surprise to meet you here! Scientifically backupped or not – it's my conviction based on own experiments, primarily with speakers in this case. Put a metal grid in front of a tweeter, and you'll hear what I mean. Even worse if it has just the openness (total area of the holes relative to the whole grid surface) of a typical electrostatic electrode. Another descriptive example are compression drivers, usually combined with a horn. If you leave the horn away, the sound becomes thinner and brighter. If you leave the compression element away, the sound becomes «normal» again, but much quiter. And much smoother, as it lacks the metallic sharpness that was present before. You can't deny that air acceleration through holes with sharp edges causes turbulences – which are prone to make the sound harsh in my experience. However, that's just one aspect of electrostatics' problems. The other one may have even more weight: the double metal plate in front and at the back of the membrane. They cause massive reflections on them and between them. Think standing waves between the stators and between stator and head/ear. Years ago I had a great listening experience with a prototype pair of plasma tweeters. Although the intergration to the system seemed somewhat lacking, the openness, spatiousness, airiness and effortlessness was breathtaking. I never heard a tweeter sounding as natural as this one again – because it was never produced. Some time later I had the opportunity to audition a prototype pair of Magnat's plasma tweeter, the flame encapsulated in a fine spherical metal grid. It sounded good, no doubt, but had a slight metallic sheen to it and lacked the naturalness and openness of my previous encounter. The final version was presented at a hi-fi show. Instead of just one metal grid it had three of them, each within the other – it had turned out necessary to shield the flame against the emission of radio waves and ozone. Now to my ears this tweeter had lost all of its justification, the sound was more metallic and unnatural than any metal-dome tweeter I had heard to date. Did you know that in the sixties and seventies many of the German speaker manufacturers used sheet metal as front guards for their speaker boxes? By and by they learned how bad this was for the sound – German speakers had the reputation to sound technical – and changed over to textile front covers, which was indeed beneficial for the sound – and their reputation. In my book the Mysphere is even farther away from on-ear headphones than typical open over-ear headphones – in that it enables the pinna even better than the latter to decode the spatial information from a soundfield that's less polluted by near-field reflections and the shell effect. On-ear headphones on the other hand barely involve the pinna as a decoding instrument – that's the main reason why they sound so «close». The next increase in this direction would be IEMs.