I bought a pair of the Audio Technica ATH-M70x's and they arrived last Thursday. Before I get to the sound let me start with the pros and cons (in my opinion) of these vs the M50x. M70x Pro: Much more comfortable fit for my big ears. M70x Con: The headband. I don't feel it's quite as comfortable as the M50x. That being said, overall I prefer wearing the M70X for longer periods of time. M70x Pro: I think they look better than the M50x. They seem to be built of a little higher quality but I'm not sure that justifies the difference in price.
Now on to the sound. I have been burning the M70x in constantly since Thursday and I can confirm the sound does change quite a bit from when I first listened to them upon opening them. Out of the box they sounded very tinny, ear piercing treble, little to no bass presence. I immediately thought to myself that these were definitely getting returned. Now after these past few days of burn in I'm not so sure. The sound has improved immensely. They no longer sound tinny, treble has smoothed out quite a bit, still might be too much for some, but just about right for me. The bass is much more present now than when I first opened them. It's just not as impactful as the M50xbl which I own but it's there, just in a smaller, maybe even more precise quality. After switching back and forth between the two headphones, the M50x sound a bit muddier and the M70x much clearer and cleaner. One thing I have noticed is I prefer listening to Sirius Talk Radio, Movies and TV wearing the new M70x. The level of clarity is just so much better than the M50x especially where dialogue is concerned. On music I'm even understanding lyrics, I had previously misheard. The M70x are definately not for bass lovers to be sure. Stick with the M50 varieties. If you like clean, clear, crisp, with a good soundstage and better mids (again just my opinion) than the M50 you might give these a shot. I will go back and forth with each headphone and think certain songs sound much more musical on the M70x and then other songs I definitely prefer on the M50x. I'll probably keep both. I think I would regret giving up the M70x's. I'll definately keep my M50xbl because they sound great and look great too (pictures don't do them justice).
On a side note there is a difference in sound quality between the black M50x I have and the blue/tan M50xbl. The BL sound so much better than the M50x in black. Not sure why. Production variations maybe. I need to sell my black M50x. Maybe I'll put them on Ebay or something.
Very nice impressions! Thanks for sharing! Not sure I would want a thinner sounding headphone than the m50x...