Well, it's possible. Headphones are easy to counterfeit so if you perhaps got them from some 3rd party Amazon seller or whatever, they could very well be fake.

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The thing with headphones is that since they basically create a tiny room with your ear (a physical audio filter) as the main piece of furniture within, your individual ears have a significant effect on how you perceive headphones, so what works well for other people may very well be unpleasant for you (which is why I personally do not buy HPs I haven't heard or wouldn't be able to easily return/resell without taking a loss). I personally really don't get along with headphones that produce excess response around 5-6KHz or so, which is where the DT770 seems to have a sizable peak, so like many headphones that a lot of other people like, I suspect I'd personally find DT770s intolerably shrill.

But pretty much all headphones can also be greatly improved by EQ, so I suggest installing EqualizerAPO and trying to tame the offending frequency response peak before writing them off, they could very well transform into terrific headphones for you. Of course, you can't use EQ with every source, so maybe they're just a bad fit for you. Oratory1990's presets are usually a good starting point: https://www.dropbox.com/s/npqrz9dqdda292x/Beyerdynamic%20DT770%20%28new%20earpads%29.pdf?dl=0