The ATH-M50x are great sounding headphones with a sound that may fall in the neutral category, but with very slight boosts to the bass and highs; a slightly V-shaped sound. The bass is full and has a lot of power. The sub bass has a hint of elevation though, which can make the bass sound a bit loo...
Audio-Technica finally updated the M50's built in cable to a detachable cable. The M50x even comes with three cables, a 1.2 m - 3.0 m coiled cable, a 3.0 m straight cable, and a 1.2 m straight cable. None of the cables have in-line controls though.
If you're looking for a headphone to keep you isolated on long plane rides, the M50x is probably not the right headphone for you. These headphones do not electronically limit exterior noises, it only blocks noise with its physical design.
Depending on which model is purchased (16/80/250-ohm), your system may have trouble powering them to get a full sound and comfortable volume. 16/80-ohm should work fine in most systems. If not, you may need an external amplifier.
The large, closed-back ear cups and strong clamp force allows for impressive passive noise isolation. Sound leakage is also significantly minimized, so these headphones can be used in office or library settings.
The 380HDs have a very strong clamp. This helps the headphones achieve better sound isolation and minimal sound leak. Although some will find the clamp very uncomfortable. Fortunately there are also many who will never notice this at all and find the 380HDs very comfortable.