On another matter, I wish to express some thoughts. I can see what was the effect of the NDH 30 popping continuously in the HD-660S2 thread, to an annoying degree for some, especially those who have never listen to it. It is an understandable reaction to express disturbance and dislike. But I think that it is not only that it doesn't let the HD-660S breathe in its own thread. It is also something more serious: Many people have spent hundreds or thousands of hours reading, searching or comparing headphones, have spent thousands of dollars/euros to obtain the best possible headphone sound or the sound that they really like. Reading that a headphone of little more than $/€ 600 could give all that they desired or more, can be very disturbing or sound outrageous because it cancels much of the previous efforts and expenses. Or even worst: beliefs. It is not easy to digest or accept. Even those who speak much for the qualities of the NDH 30, have approached it with some (or much) suspicion and disbelief (me included). But then, after the initial surprise, careful comparisons started to reveal much more sound quality and maturity than ever anticipated - at this "very low" price. Moreover, those who want to buy their first (and possibly their only) top-of-the-line headphone, feel insecure or that there is a great risk, if their hard-earned money are spent to a headphone that may only bring them half-way close to their target. They may need the "safety" of spending more than enough.
Endless arguments are of not much use in the case of this headphone. If its "supporters" are right it is not easy to prove it with words and posts. For the NDH 30, the only way to see the bold and unexpected advancement that it brings for "offensively little money" is to listen to it and compare it - but with the best sources possible (it is not at all power hungry but it will let any high-end source/dac/amp shine).
Another thing is that this price may provoke a "war" of impressions from other manufacturers and affected dealers, since it demonstrates clearly that there is no need for multi-thousand dollar products to obtain a rare and very admirable sound quality. This may prove to be an even more difficult problem than suspicion or disbelief. Only if one or two more manufacturers decide to offer similar quality at similar prices, we may get rid of the hype in headphone prices that is so intense during the last 5-10 years. Not an easy task though, because headphones are the "new cables" now. Prices will go as high as (ignorant) buyers are ready to pay.
Enough talking, I cannot stretch anything else more than this: Do not buy that "rude" headphone, just try to listen/compare it with the best headphones and electronics that you can. Let only the facts (your facts) convince you, not our posts.
Enjoy your music, live and recorded!