You can't expect anything even remotely close to perfection in mid-fi. Of the candidates, the X1 makes the fewest compromises.
Unless you actually find the sound signature completely disagreeable or need a closed headphone, it seems like the pretty obvious champion to me.
I believe the X1 is sufficiently proficient that it bends the usual rules of subjectivity and preference.
I agree with the reviews. Its a really ambitious head phones, i imagine how the senior program engineers / architects must have presented on the white board a agressive project goal: open back, big sound stange, good instrument articulation, spacious sound stage, big bass without bleeding into a quite present and not muffled mid, more so impressive and really unique in itself is its fastness and sound stage even at a 100 Db SPL @ 100 mW @ 32 Ohms considering there is no damping factor to it or scalability aspect with a good amp unlike HD 600 or 650.
Yes one would argue with a good amp to overcome those 300 Ohms, X1 dont come close to 600/650's sound stage, depth, instrument arcticulation, bass extension and tightness. but without a decent portable, both 600/650 doesnt sound half as breathing and open as X1.
All and All, I feel its an honest attempt to pull it off so nicely. Yes its jack of all trades, but some jack it is!! its not headphones that impresses you very much on bass accuracy extension, or sound stage, or instrument articulation, or neutrality unlike LCD2, HD800 or HE-500. but it sure makes you go "hmmmm,, this is interesting!!" in few minutes of listen. cause its genre of its own. its not a stone cold follower of anyone league yet it tries to pull off everyone little bit for a mid-fi headphones! Its like i can relate to a personal experience of pulling of a project with limited expirience engineers in my team trying to develop a software with features and performance that rivals one made by the likes of geniuses like google or Apple and yet able to respectfully earn a position.
Honestly i feel if they were able to pull of this weird tunning to their drivers, than a neutral flat signature would have not been tough either.
Philips have indeed done a good job, honest, humbly and sincerely pulling this off, entering a league where its even getting discussed in this forum when it used to be a walmart side shelf 20$ audience targetted company!
Remember to keep this in perspective and salute them!
Good observations and interesting comments. I think I'll hold off on this headphone until I get to hear it at a meet.