To answer some queries I've noticed previously, the company which makes the Fidelio is actually called WOOX, a former subsidiary of Philips, based in Hong Kong, which was spun off to solely develop high end, fashionable audio devices. In the summer of 2014, it was sold to Gibson, yes of the guitar fame who also happen to now own Onkyo, Cerwin Vega and other studio equipment companies.
Nice info.
I did not know that, but I had the suspect there was some connection when I have read this some time ago:
http://www.cnet.com/pictures/best-new-wireless-bluetooth-headphones-of-ces-2015/16/
The look is not the same (even if, something in the cups could be similar), but the name...
I finally sent them back. For these reasons:
I have tried the Audio Technica ATH-WS99BT, and they destroy the M2BT. No comparison possible. The ATH are much better in everything.
The only thing where, to be honest, the M2BT are still the best BT Headphones ever (together with the UE9000) is the sub-bass. M2BT and UE9000 have a deep, full-bodied sub-bass, with a dense/solid rumble, which I have not found in any other headphone.
The ATH is more balanced in the bass, being even less bassy out of the box, but able to give an astonishing amount of bass when EQed. Really impressive, the most impressive bass of any other BT Headphone I have tried.
Compared to M2BT and UE9000, the ATH have a more impactful and clean bass with a better balance of Punch and Rumble (also, less subby than the other two, but still subby enough). They have anyway MUCH better mids, of an incredible precision and presence, and very clear, clean highs, with zero sibilance (which I cannot say of the Fidelio).
I would have very very happily kept the Fidelio as my portable pair, but the slowliness of their power button (very slow in connecting, and extremely slow in turning off), plus some occasional connectivity problems, plus the very annoying very bright pulsing LED light, plust the absolutely idiot Power Button which once you have them in the backpack makes them turn on alone if something presses on them, plus the very poor range (ok, this is not a problem when you use them with your phone in the pocket, but, still), plus the horrible Customer Care, made me say "ok, do you know what, I look for other solutions".
And AKG appeared with their Y45BT, which are MUCH more portable, have better mids, costs the half, comes with a very nice circular soft carrying case, have a ultra fast power button, very nice bass (not as the Fidelio, but nice enough to live with them as "on the bus" portable pair), and actually same mediocre highs with same tendency to sibilance.
So, for now I am very happy with this two Headphones.