FWIW I owned both the 371 and d5200 at the same time, and the d5200, in my experience, is miles better than the overrated 371, both in original FR and after DSP.
To the question OP asked in the previous page, which I presume some other people might wonder too: "well if we EQ headphones A and B to said target then HOW can one sound different/better than the other? They should sound literally the same!!!"
I am very keen on the idea that FR is not the "be all, end all" of how and why we could perceive differences, whether it's reliable or not. Just think about it, if all it takes is proper EQ to make all headphones sound the same, then why don't all of us in the objective-camp here buy anything other than the cheapest headphones available? (yes I know there are other factors like usability, comfort, etc...) Doesn't that make the 371 or any other headphones obsolete because we *only* need to EQ it precisely to the *target* we want? Even with all the BS and shadiness in the audiophile community/industry, they all would have gone bankrupt if a $10 headphones can sound exactly identical to $100, $1000, $10000 or whatever prestige level, design pattern there is.