Pros: Plenty of bass, excellent clarity, wide soundstage, detailed and very affordable, awesome build quality
Cons: piercing treble and can sound thin in comparison to smoother cans, recessed midrange, non-detachable cable, clamp a little too tight
I got these on Amazon for just £68 (sterling). Ridiculous right?
Let's get the bad out of the way first.
They sound thin and a little shrill because they have prominent treble. While they sparkle and sound very exciting first, the piercing highs become irritating and if your volume is high enough, you start wincing in pain as those high frequencies wreak havoc on your poor eardrums.
The clamp is fairly tight and after a few hours, you'll start to feel it. The midrange is pushed back. Combined with the wide sound stage, vocals can sound distant. When listening to vocal dominant music like soul and r'n'b, this can really take away from the listening experience. A more forward sounding can would really wow you!
The cable is not detachable but it's built rather well. Aside from that, I think the headband is replaceable and so are the pads. If you take good care of it, it'll last for several years.
Now to the good.
The bright side (no pun intended) is that you catch a lot of detail, especially with the instrumental side of things. There's just so much sparkle - it's an exciting headphone.
The trump card is the bass. Most open cans don't reproduce a great amount of bass, but this is the exception. For comparison, I also have an XB700 which is about as much bass as you'll ever get out of a CLOSED headphone. While the DT990 PRO isn't a match for the ridiculous XB700, the bass rich, extends low and even packs some mild impact. Where the XB sounds muffled, like listening to music with a towel over your head, the DT990 PRO is clear and the bass is definitely powerful. Drums hit hard and possess a satisfying thump (I listen to hip hop mainly). It's a fantastic can.
Also, the expansive soundstage makes music so interesting. Instruments come from every direction where other headphones reproduce a more linear sound. These are far more dynamic.
I've since sidelined my DT990 PROs with Philips' Fidelio X1. A very similar sound signature with smoother treble and a more forward midrange. The perfect headphone in many ways, but for £68, the DT990 PRO is 80-90% as good as the X1 which cost £150. Then again, the X1 is one sexy looking can!!
Still, my DT990 PRO is a cherished can which has its place in my collection. It was my first fully open headphone and it introduced me to a new level of sound. Now I can barely stand my XB700s and my ZX700s due to their closed nature. I just don't enjoy that kind of sound anymore. I have been spoilt!