I considered it, and know that some here like that configuration. But my Fostex knock off grilles already were stripped down, and I didn't hear any convincing difference, although the total time put in wasn't that great, so maybe it's a good thing. I have to say "closed in" is a biased term. I might counter with "loss of the rear plane of the recording space". Even at the three best concert venues I know for acoustic music: BSO, Carnegie, and Mechanics Hall (Worcester), there is a boundary, reflections, diffusion and absorption. The notion of a note playing with no baffle seems pure from a conceptual standpoint, but in practice you've got to think about what you get vs what you lose, and what the designer had in mind. I like "open back" headphones because they seem to image better, seem more real - but "open back" is a term, all open back headphones I know actually are not totally open, just not closed to a lesser or greater extent. Or if you prefer "tuned". I like that. Are all cans tuned to the best level possible? No. And of course your perfect and mine are two different animals. So there is room for mods - but I've learned to be clinical about it. Remember the King has no clothes when it comes to what we want to be true - or the assertion that all changes must be good.