Funny you this question should pop up as I was in the same boat a month ago, sort of. I had the M50x's for about 3 years but over time the clamp weakened and they became really uncomfortable, almost unbearable for long sessions because of the way they sat against my ears. Anyway, I went with the DT 770's to replace them because they looked comfortable as hell and are highly praised.
I will cut to the chase right here. As an owner of both, the 770's are MUCH better than the M50's.
I, like you, am a fan of bass but I'm not a bass head and I prefer bass to sound more accurate than all over the place and muddying up them mids, and the 770 32 ohm is great for that. The bass is strong on songs recorded that way, which is how it should be. Try a track with really good sub bass and you will be amazed. Supposedly the 80 ohm version has even more bass but I find the 32 ohm to have enough. And they stay in their own space. The mids, people say they are recessed, and I think they are just slightly, maybe a little thin and hollow, but not enough to be a deal breaker. My only complaint with the sound signature is that, while the treble is clear and detailed, it can get a bit peaky, especially in the sibilance region. Tracks that have a little bit of sibilance will have more on the 770's, but again, I PERSONALLY don't think it's THAT BAD, but it is noticeable, so if brighter treble/sibilance bothers you proceed with caution. I found it kind of annoying out of the box honestly but it's settled down quite a bit after a month and it tends to only be a minor problem on bright recordings. One way to put that, the headphones are doing their job, and are revealing. But the treble is also good because it adds a crispness and airiness that lets all the sound breathe. Soundstage, is AMAZING. THIS I was blown away with, because the soundstage is crud on the M50's. Also way more detailed.
If you like a lot of mid bass that is colored and a darker sound signature go for the M50x's, but the 770's sound much better imo. Cleaner, drier. In fact just now I tried listening to my M50's again and my first thought was, why did I think these sounded so good? That's not to knock them or anything but going between the two the 770's gave a much better representation. The M50's sounded muddier to me.
I hope you get more opinions, but I personally would say get the 770's. They're all around better than the M50's, the only thing the M50's have the 770's don't is a more relaxed treble, but they also sound muddier. I didn't like how snares sounded on them.
The 770 32 ohm are currently sold with velour and pleather pads I believe. I'm sure the pleathers are comfortable but Beyerdynamic is highly regarded for their comfort with the velour pads so I got those. The pleathers should give you a little more bass, but you will lose a little soundstage. Just something to think about. But, these are among you can get in their original price bracket of $250. Now they sell for around $150 so at that price they should be a steal.
Hope this helped!
But, even though they aren't for everyone I think most would agree the 770 Pro are a great headphone, especially for $150. And you can't beat those luxurious velour pads!
