Inspired by @Chrono’s review above, along with other opinions regarding this headphone, I stopped for a while to put this headphone into perspective and think about how I actually use the DT1990 Pro and what I think of it.
I have owned the Beyerdynamic DT1990 Pro for approximately 18 months now and together with the Sennheiser HD6XX, they have become my reference point for over ear headphones, certainly not because they are perfect but because they are the headphones that I use mainly.
The sound signature of these two headphones,along with their strengths and weaknesses, are completely different between themselves, therefore I am not going to go into comparisons between them, I am going to focus on what I think of the DT1990 itself and the circumstances in which I actually use this headphone.
Let me start off by saying that my experience in the audio world has been extensive but not really headphone related until recently, where I finally moved over to listening to headphones due to changes in my personal life. Audio has been both my job for over 20 years and my hobby for far longer, starting out as a vocalist (I don’t think I can use the term singer as it was Hip-Hop music) and getting onstage for the first time at 16, although I remember getting my first “HiFi” system at a very early age of about 6 years old (which certainly wouldn’t be considered HiFi now).
Over the years I have worked mainly in the install of large audio systems for theatres and show lounges, while also working on live events, in studios and other smaller places. At the same time, outside of my main job, I was performing on stage until around 5 years ago when I decided that I needed more sleep, having moved from being a vocalist (or a fast talker with rhythm 
) to a bassist, with a few years as DJ thrown in the middle.
Why am I rambling on so much about all this? Well, I think that it is important to put into context that my history in the audio field has been much more related to live and studio terms than it has been sitting back and enjoying recorded music. Don’t get me wrong, I have always loved listening to music and have done since a child, but my music equipment purchases and experiences have been focused on equipment to be used as tools with the personal listening experience taking a secondary role. As an example, my home audio system until a few years ago was a 10.000W PA system that I would set up on my patio (needless to say I didn’t have neighbours then!).
So, on to the headphones… finally!
It has been a long time since my unboxing experience of them, so I can’t really give you a first impression, but I can say that the headphones were well packaged, with a nice selection of useful accessories in the box (such as a carrying case, two cables, two sets of pads) but packed in a way that is functional and simple.
The two cables included were one straight and the other coiled. Although I am probably in a minority, I actually like coiled cables, especially for studio use, as it saves a lot of “ooops” moments when turning around or reaching over to press something.
The carrying case is again very functional, it not only stores the headphones but also includes a space for the cable and adaptor, along with a compartment for the set of pads that you are not using. This is very handy to keep everything together and while I wouldn’t consider the DT1990 as portable, it makes it easy to grab everything together when moving between studios or similar.
As far as build, the DT1990 are a headphone that seem to have been built to be abused. I have not abused them personally, but they are certainly not headphones that I would be worried about handing over to anyone to use, I think you would have to really try hard to break them. They are practically metal in their whole construction, you have to really search to find anything plastic on them, and have a fair bit of weight to them due to this. At the same time, they are well balanced as far as comfort and the weight doesn’t really become an issue, at least for me.
Sound…
Here is where I might go off track in comparison to many of the other reviews regarding these headphones. That is mainly because I am looking at these from a tool point of view more than a enjoyment part of view (although I do enjoy playing around with music), I will explain a little more about this in a moment, but here is what I find in regards to the sound…
As mentioned, there are two sets of pads included with the DT1990’s, named “Analytical” and “Balanced”. I am not going to comment on the sound differences between the pads as it is so long since I listened to the “Balanced” set. When I first purchased the headphones, I spent some time going between them and settled on the “Analytical” pads that I have used ever since.
In regards to bass, I find that the bass on these headphones is very clear and detailed. They extend pretty low, maybe not into the rumbling territory, but at the same time manage to keep the bass clear and defined. Playing around with the layering of different bass related instruments, I find I can easily locate and edit each layer. However, if I end up layering too much in the bass area, I can end up with something that starts to get a little muddy and loses definition.
Saying this, when taking the same layered tracks over to bass heavy speaker set ups (which, let’s face it, is the majority of systems that normal people favour in this day and age), I haven’t yet found these systems to define these frequencies any better, they certainly don’t clean up the mess I have made and make it sound much better than on the DT1990.
Moving to the Mids, I find the mids to be very accurate and pretty neutral, except for a slight boost where the upper bass moves into the lower mids. This is something that I have come to find that I like, as long as it is not overdone, as it (when the overall timbre is correct) helps give life to stringed acoustic instruments, such as acoustic basses and guitars. When playing and recording bass guitar, both electric and acoustic, I find that the frequencies between 100Hz and 300Hz are where most of my attention is focused on, mainly because that is where the majority of the first harmonics of the lower bass lie, and the area were they are (usually) more distinguishable.
I have no issue following bass lines on even the busiest of tracks through the lower mid range, making it easy to spot mistakes (which is not always a good thing 
)
Throughout the rest of the mids, I find that they are pretty neutral, maybe there is a slight boost somewhere right at the top of the midrange where the treble starts, but I find that it is very slight and not always noticeable unless something specific is happening in that exact frequency.
Moving up to the infamous treble…
This is where Beyerdynamic gets stones thrown at them from all angles, probably justified in a lot of cases, but again, it is a question of perspective.
As far as frequency response, I think that anyone who has ever heard the name DT1990 Pro knows that it has a treble spike at around 8.5kHz. This spike will affect some people more than others, however, there is no denying that the spike is there and it is rather large.
In comparison to other Beyerdynamic headphones, it is not as bad on the DT1990 Pro as other Beyer offerings. I have not had extensive periods with many Beyerdynamic headphones but this is something it is easily spotted even in brief listening sessions or quick tests. But, just because it isn’t as bad, doesn’t make it right, far from it. This peak causes sibilance in parts that are bright of their own nature, making “S” be extremely uncomfortable at times, in tracks like “Only Time” by Enya and “Hope Is A Dangerous Thing” by Lana Del Rey, it can take all the enjoyment out of the track, that is without even considering tracks like “China In Your Hand” by T’Pau, which can be torturous.
Some people actually say they like the Beyerdynamic treble, where as other think those people are crazy, or deaf, or both. All I can say is that there is no accounting for personal taste and if someone likes that peak, then I am sure that the DT1990 Pro is probably the best option for them in it’s price range without a doubt.
In my case, I need to clearly distinguish between work and pleasure. When I am listening to music for pleasure, I have an EQ preset in Foobar that is simply a a 8dB cut at 8.5kHz. This is because when I am listening to music, I am more of a person that tweaks EQ to taste depending on both the track/album I am listening to and my feelings at the time (there are times when I want more bass, others when I want less etc.), therefore the 8.5kHz cut is sort of a blank canvas more than anything else. Just to be clear, when I am listening to music for pleasure, I am listening to it for my own pleasure, therefore “how the artist intended it” is something that takes a back seat (if you want to know more on my thoughts about this subject of EQ, you can read this post: EQ? Anyone using one?)
When I am using the DT1990 Pro as a tool for work (I say work, but my audio editing and mixing is done solely for pleasure at home nowadays anyway, I just think that it is good to differentiate between the two cases in which I use the DT1990) my approach is different and I don’t actually add any specific EQ to the headphones. I have said before that it is possible to mix music on any headphone of speaker system (within reason) as long as you get to know and learn to read what you are using. Until I moved to the DT1990, I was using the AT-M40X for mixing at home, and because I had used them so much, I knew how they translated on to other systems. The same goes for the DT1990, which I have used extensively for a long period of time now, I do not need to compensate the treble in order to know how it will sound on other systems, as it is an automatic thing I now have in my routine. Basically, if I can get it to be on the verge of sibilance on the DT1990 Pro, then I usually find it to be about right on other set ups (at least the ones I get to try).
@Chrono mentioned in his review that there are two points of view, one is that it is “highly detailed” and the other is that it gives “a false sense of detail”. In my humble opinion, and remember that I am talking about this from a “tool” point of view, the DT1990 does not invent detail, in other words, for you to be able to spot something using these headphones, it needs to be there in the first place. However, due to the peak which is in question, I feel that the DT1990 moves the focus point on to a different part of the spectrum, highlighting (perhaps too much) this frequency range which causes it to seem incorrect to those who listen for pleasure while perhaps making it easier for someone who is working on the production of the music. That 8.5kHz frequency is right in the middle of where sibilance is found in vocals, which is far too easy to be overlooked if the monitoring system you are using does not cover that range well, and personally, I would rather remove to much from there than not enough (always within reason of course).
Other performance related subjects…
The soundstage of the DT1990 is wide without being overdone. It gives you a feeling that you have speakers off to the sides, however, it never makes you feel like you’re at the front of a large concert where speakers are way off to the left and right. As far as the imaging, again, I find that I can easily place instruments but without getting the feeling that I am amongst them, I always get the feeling that I am listening to them through speakers, I mean, I do not find myself immersed in the music surrounding me, I never lose the sensation that I am in fact sitting in front of the music and it is being played back to me.
With regards to timbre of instruments, I find that they are very realistic in 99% of cases, the 1% remaining is when the specific instrument has a lot going on in that area just where the high mids meet the low treble.
My conclusions…
The DT1990 Pro is not a headphone that I would recommend for someone to sit back and enjoy the music, for that, I enjoyed the Sundara much more, which has just as much detail as the DT1990 but presented in a different way (I referenced this in my Sundara review here: Hifman Sundara Open-Back Planar Magnetic Headphones - Official Thread)
The DT1990 is more about focus. It doesn’t invite you to sit back and relax, it makes you sit up straight and think about what is happening, and this can get very fatiguing if it is not something you want to do at that moment.
Whereas other headphones (such as the Sundara or the HD6XX) are similar to listening through a nice set of HiFi speakers, the DT1990 Pro is like listening through a set of very revealing studio monitors in a well treated space. Over the years, most of my experience has been with Genelec Studio monitors and Meyer Sound live rigs, which I have grown to love and have become my favourite systems but can both be overly hot in the treble, especially Meyer, if not used accordingly. I am not saying that the DT1990 are the equivalent of having 10.000€ of Genelec monitors set up in a perfectly treated studio, but I can say that they are something that I can quite easily use to get to know exactly how the music will sound on those Genelecs.
A large part of this is getting to know the headphones and the speakers, knowing how something will translate from one system to another is like learning a language, there is a difference between speaking a second language, being fluent in a second language and being bilingual. I would say that the DT1990 Pro place themselves in the fluent category in relation to high quality studio monitors, without getting to the point of being bilingual.
They are not perfect as far as studio level monitoring but are certainly a high quality option and, let’s face it, some of the most used Studio Monitors in history were far from being perfect, with some of them being pretty terrible as far as music enjoyment (cough, Yamaha NS-10, cough), but great music was made with them. I would put the quality of the DT1990 Pro way above almost anything that was available for studio use until 10 years ago (and that includes monitors) unless you were willing to invest tens of thousands in monitors and room treatment.
For music listening and enjoyment, they would not be on my go to list, and while they are my most used headphone, they are not my pick when wanting to sit back and relax to some tunes.
(This review / impression is also available in Spanish on my blog, link in profile).