DT 770 M (80 Ohm)

On PC and I run BeyerDynamic DT770s headphones at 80 ohms with a Schiit Audio (name always cracks me up but they make good stuff) AMP & DAC. I've kinda went back and forth on the Dolby Atmos stuff for emulating surround sound on headphones. It does seem to be better in Arc Raiders but sometimes gives some weird results. I got a cheap boom stand and Samson C01 mic on it above my monitors. It sounds great and doesn't pick up much ambient noise and since it's up there and mounted on the back of the desk I don't have to fool with something on my headphones. In my experience with any "headset" style combos you are just paying more for worse equipment than if you bought them seperate. Before I got the AMP and DAC I ran a pair of Audio Technica M50X headphones and a cheap Logitech desktop mic and that was miles ahead of any Turtle Beach or Razer headsets I had prior. I did have those Razer Tiamat headphones that had the seperate speakers and did "true" surround sound for a while and they were kind of a pain in the ass and kept shorting but made you feel like fucking Daredevil on Battlefield.

The blue curve does not at all look like the bass response from an open-back. This would be technically basically impossible. I think you might have confused it with the DT 770 80 Ohm, which is closed-back. There are some newer open-back high-end models who achieve a subbass boost without influencing the mid bass, but definetely not a centuries old mid-fi headphone like the 990.

Having looked at a lot of frequency response graphs, I am not aware of any open back dynamic driver over-ear headphone which was released before 2020 which has a real harman-ish subbass followed by a harman dip at ~200hz. Even up until today only very few headphones come to mind. Can you give me any example? And would you not agree that the blue graph rather looks like the 770 80 ohm? (Does an 990 80 ohm even exist?) The 990 is known to be mid-bassy with a rolloff in the subbass, you own measurements show this too.

Star small brother, figure out your tastes in terms of audiophile vocab before dropping big bucks on anything. Build out your setup in terms DACs and Amps, prob start with something like a portable bluetooth DAC/AMP. Then get some IEMs and some over ears that your portable unit can power and work up from there. I’d recommend a Fiio BTR13 or a BTR7, and then Artti T10 IEMs and the Beyerdynamic DT 770 80 ohms as your over ears. 

If you don't like a very wide sound stage I would stay away from the X2HR. For me, it is too wide, makes the music sound a bit shallow. And their treble sounds a little bit metallic too. The metallic treble is less noticeable than the very wide sound stage. They have a good, punchy base, but I prefer DT770 80 ohm's base, especially the sub-base rumble, which X2HR lack a bit. They are very well rounded headphones though. I would recommend you trying them.

Yes. Those are de facto industry standard now.