After the long service life of the Audio-Technica M-50x, they endured much abuse and eventually started to lose volume/frequency response out of neglect.
Now is the bittersweet time for something new. I put my trust into the former AKG engineers at Austrian Audio and went all in on some Hi-X55s, their only closed-back monitor headphones. Dry. Very dry. Just the way it should be for monitor headphones when all you're looking for is inconsistencies and problems in your mixes. I listened to a few older tracks and it became VERY apparent I didn't notice some resonances, or just "ugly" sounds. The bass response on these are nice. However, if there is a "juicy" amount of bass in the track chances are there's too much after comparing to chart toppers and popular music. Such was the case after running the mix through a sub-woofer equipped sound system. Could barely hear any of the other sweetness of tracks. So it's important to note that the bass SHOULD be lacking when mixing in these. The frequency response curve is there for a reason.
Other than that the stereo field is WIDE. If there was any M/S processing in a track it becomes very apparent. I'm starting to love these cans, but do not expect to jam out to new songs you hear. These headphones are a tool...very precise at that. They'll show you harshness you thought wasn't there. Overall I'm very happy with purchasing them.