PROS 1. Sound quality. Highs are crisp, but not too bright; mids are well-presented; bass is punchy and tight. 2. Build. They feel solid and ergonomics are great. There is no complex suspending system, so there is nothing to break. 3. Portability. Both cups rotate horizontally at 180° and also fold vertically to make the headphones' dimensions quite small and portable-friendly. The supplied pouch comes in handy. 4. Unlike their predecessors, ATH-M50X arrive with three detachable cables: a long straight one (you can use it to connect to a source that is further away), a short straight one (very handy when connecting to a smartphone, or if your computer is located very near to where you are sitting), and a medium-length coiled cable (very versatile and my personal favourite). The insert-and-turn locking system secures the cable to the left cup. 5. No sound leakage. These are closed-back headphones, so you can use them in a room, filled with people, or while commuting, without any worries that you might disturb someone. 6. With an impedance of 38 ohms you do not need a headphone amp to drive them.
CONS 1. Cable connectors are proprietary. But then again you get three cables in the box, so it is unlikely that you will be looking to buy new cables any time soon. 2. At 285 g plus the cable, the ATH-M50X feel heavier than similar-sized headphones I have owned. They are almost entirely made of thick rigid plastic. 3. I have watched video reviews, making the argument that the ATH-M50X are not exactly audiophile quality (that is, their response is not as 'flat' and 'neutral', as it should be). This could indeed be the case, as Audio-Technica has other models (like the ATHA900X), positioned in the higher and more expensive segment, but the latter are not meant to be carried around. In my opinion ATH-M50X have been built to produce enjoyable (rather than analytical) sound. Consider this carefully. 4. ATH-M50X's greatest drawback is their lack of comfort. These are actually on-ear headphones, so they do press on your ears and the pad’s faux leather will make your ears hot. M50X are sturdy, but also a bit heavy and rigid. Compared to Philips X2 Fidelio or AKG K702 (both of which are true over-ears headphones), M50X leave much to be desired in terms of comfort. 5. At £125 they are too expensive.
CONCLUSION 1. Audio-Technica ATH-M50X are the overall winner if you are looking for an enjoyable, full-bodied sound, great portability, a sturdy build, detachable cables, and a no-nonsense look. 2. The only real let-down is comfort. The cups are smallish and press on your ears. Pain will start to appear in 20-30 minutes and your ears will get hot. 3. Finally, there is the price consideration. On November 24, 2015 these headphones cost just £87.66. At that price they were unbeatable. At the beginning of February, however, things changed dramatically and not in a good way. Please, be advised that if you are ready to spend £130, there are other—better sounding and more comfortable—headphones available on Amazon: the legendary AKG K702 come to mind. It is true that the latter have a leaner sound (less bass), a higher rated impedance and have not been engineered for portability, but at the end of the day sound quality and comfort are the two most important characteristics of a great pair of headphones. 4. Audio-Technica ATH-M50X are still a recommended buy, but I would advise acquiring them if and when their price goes down to about £90.