I own a pair of m50x for years, and I absolutely hate the pair. It's soooo overhyped.
Sure, it is a fabulous pair of headphones--for professional studio use, since it's a pair of MONITORS. All the qualities are tailored toward that end. It's flat, it's dry, it's boring, but it's extremely accurate and cost-effective. Hence, they suck at almost everything else aside from recording or mixing. I'm not saying m50x is a bad pair of headphones--far from it; the sound quality is superb--but they are built specifically for a even more specific group of industry professionals which most of us aren't a part of.
If you want enjoyment and COMFORT, seriously, look elsewhere.
However, sound, enjoyment, and comfort are very subjective... and they really are a great pair for the price. I hate them, but don't regret ever owning them. So... take them or leave them, both at your own risk.
Personally, I've longed outgrown my m50x into a pair of DT1990 Pro, and not looking back at all.
I have an ATH-M50. It's a very old one without the removable cord.
A: Coiled cords SUCK SO MUCH. I can't remove my fucking cord-- even worse, the tangling is permanent on it.
B: Durability and quality of audio is EXCELLENT. I've had it for years. Years!
The only downfaults are the end of the cable ( spring inside can get messed up and torn out ), headphone cushions ( torn up to hell and back ), and the headband over your head ( torn up, but still holding )
Audio quality still holds up but there is no "thumping" when you put it on full blast
Edit: Here it is, discontinued http://www.amazon.ca/Audio-Technica-ATH-M50-Professional-Discontinued-Manufacturer/dp/B000ULAP4U/ref=sr_1_3?ie=UTF8&qid=1456344626&sr=8-3&keywords=ath-m50
They don't have a flat frequency response, at all. They're flatter than something like a DT990 but they are very much so bass and treble headphones. Mids are recessed, very high, highs are there. "Dumb" video. Somebody is a fanboy. Why would you make bass heavy headphones for monitoring?... You want flat, analytical so that you may make the music as you want it to be heard.