beyerdynamic DT-990 Pro 250 Ohm

Originally I bought DT990 Pro to use in my synth set-up (without a computer) but the coiled cable quickly became problematic, so I plugged it into my computer, replacing DT770 as mixing headphones.

My first impression when I played some music was like: "My ears! It hurts!" because of the amount of high-frequency content. This was the reason to do the first test with high-frequency rich genres like Trance and Techno.
Here are my observations:

Trance is the most unbearable to listen to. About 90% of tracks attacked my ears with ear-piercing cymbals. It's better with Techno but I got mixed results here as some Techno tracks are more muffled and some have boosted high-frequencies as in Trance music. Besides cymbals like razors, high-frequency content didn't have good separation and it sounded like all cymbals are just one huge mess.
The low end was ok in most cases. It didn't have impact, weight or transient as DT770 but it is there. This is what I thought before I moved to the other music genres.
My other impression was that I don't hear any more stereo space in these headphones than in DT770, which is ridiculous as 770 are closed and 990 are open. I should be able to hear a huge difference.
I tried MP3s and uncompressed flac/wav files. I couldn't stand compressed music most of the time. I'm forgivable in that matter but on DT990 I could hear much more unpleasant artefacts that together with the not-so-great production quality of Trance make the listening experience much less fun than with consumer-grade headphones or even DT770. After listening to more than 100 Trance and Techno tracks I had the feeling that some of them were made or at least tested with DT990 because they were sounding good while others (even those from famous producers) were flat, lifeless and sounded like coming from a tiny box.
To summarize my impressions of Techno and Trance: the majority of tracks in these genres sound bad and unpleasant on DT990.

The second test was with a variety of genres, from Jazz to Ambient, Pop, 80's etc. Here's where "the fun" started. I tried a bunch of reference music for audiophiles out of curiosity (I'm not one of them!).
Immediately I could hear a wide stereo space with instruments filling it from far left to far right. Trance and Techno at best have half of it which is a shame. I could also hear dynamics and "vertical" space between vocals and other instruments in or close to the centre. Another thing that genres in my first test lacked. And I can't blame only dynamic compression which is usual;y too high in modern electronic music because this problem appeared even in older tracks that I know weren't treated with compressors (or just a tiny bit).
DT990 Pro revealed its full glory in this test. Horizontal and vertical space became filled with the joy of good sound. Of course, high frequencies are in front too. DT990 has simply too much of it. But at least it didn't hurt my ears.
The low end is a mixed bag. In some tracks, I missed more of it but I could still hear the punch/transients. Also, genres like Jazz are not bass heavy in the first place. Genres like RnB gave often different experiences. The bass guitar was often enormous and put Trance and Techno to shame. Who could think that "bass genres" will lose to 80's Pop songs? It's probably because DT990 has boosted mid-bass but it has a very good bass extension so it should give genres with sub-bass more "oomph" than I experienced.
DT990 Pro are definitely better with non-electronic dance music genres if someone wants to buy these headphones for casual listening.
Another story is studio use and critical listening. These headphones can reveal every (or at least a lot of it) detail, badly done mixing and mastering. I don't know how they will work as mixing headphones (I'm still on holiday and too lazy to check) but I can already feel that a correction curve will be necessary to at least attenuate a bit of high frequencies. Otherwise, mixers may try to attenuate high frequencies more than they should.
To summarize:
I wouldn't recommend DT990 Pro for casual listening. Most of your favourite songs may be unbearable to listen to. Besides that, as long as you can still hear a high frequency range up to 16kHz as I do, this part of the spectrum will be always taking the space and in front position.
Some people may enjoy genres like Jazz, RnB etc. on those because of the wide stereo space. As long as it doesn't have exaggerated cymbals, you may be fine. If you prefer deeper, more towards mid and bass range sound, avoid DT990 at all costs.
For critical listening, these headphones seem to be alright but once again, high frequencies are spoiling it. Same problem for mixing because besides that, separation in high-end is not that great. I wouldn't recommend DT990 as the only mixing reference for genres like Techno or Trance.

I bought the Beyerdynamic DT-990 Pro as my third option to reference my mix and also work with my music at night. I produce Techno and Electronic music mainly.

The comfort with this headphones are amazing, you can literally work with them for hours without fatigue, in a sense that you forget wearing headphones.

The quality is decent close to high quality standards in that range of price. The headphones are light and not heavy because of the plastic material, the only metallic piece is the one which connect them to the head holder. The downside of the quality/build for me was the cable which is not removable.

The sound is overall unbalanced!!
The low frequencies are round, warm and pleasant to listen but they lack clear definition and makes it difficult to mix.
Mid frequencies are decent like the bass clear but colourful and they are getting shadowed from the high frequencies which is the main problem with this headphones.
The high frequencies are enormous high, harsh, metallic and you can literally have fatigue despite the comfort the build is giving you.
A no go for mixing.
A small yes for listening but you might need to look for headphones amplifier and do some eq before listening to any music.