[0rpheu]

Hi folks, i just diagnosed a problem on the ATH-M30x and M40x they have a weak point where the cable that connects the right driver breaks, that's the reason for all those people suddenly not having sound or lower volume on the right side, basically if you collapse your headphones every time you store them of very often after you use it will break the little cable the connects the right side, after a year of use my pair broke, i just sent them to audio-technica because they where still on the warranty, but it's an easy fix if you can use a soldering iron.
the weak spots are right here:

I hope this information can be helpful, it's a design problem and Audio-technica's fault they should know better, other than this the headphone are sturdy and have a good sound for the price.