I have the ath-m50's and the hd 380 pros. I like them both, a lot. The two are completely different headphones. I'd say each at the opposite end of the other. I use the hd 380 pros at work, the ath-m50's at home. Not sure why but I prefer the way they sound this way better. I do wish the ath-m50's had the replaceable cable. I got the straight cable version, wish I would have chosen the corded one but no one carried it around here. If I had to choose between the two, I'd probably choose the ath-m50 for just one reason. The hd380 pros have that Sennheiser veiled sound. I like it, for some reason like it better at work, smoother more refined but more expensive. The ath-m50's seem clearer, more up front, better value. Both very comfortable wearing a long time. I do agree both sound much, much better after about 50 hours of high volume burn in.
Yeah, they're both-
Oh boy, the mythical Sennheiser "veil" yet again. =\
Anyway, they each have their ups and downs versus the other, you should give both a try if possible, johnvonmacz.
Edited by Mad Max - 9/2/13 at 3:14pm