It's in spain though they don't use imperial unless they were buying trains from USA. UK already uses metric in engineering.

Damn I wasn't aware of this. I saw some open source community data banks with corrective EQ curves for a bunch of headphones. I'm sure you can find it if you do some googling. Also if you have a solid curve from sonar works already you can just try to copy it best you can into the EQ APO. Good luck and may the good sound be with you always xD.

Well yeah but compared to any gaming headset they are still fairly neutral. I mean I've linked reviews with EQ response graphs for a reason.

DT 770 are fairly dry, neutral and with not much low end boost, especially for closed back headphones. Logitechs are probably tuned to be less neutral and to add some spice, most gaming headphones are that way, just how things are.

If you stuck to the DT 770 after a while, you would find the Logitech ones weird and bass boosted.

Also, I'm not sure how these two compare in terms of imaging, distortion etc.

Another thing is the quality of the source files, and the entire audio chain. Maybe the source files are compressed, or the PC wasn't set up with the highest sound resolution and bit depth. The thing with good headphones and speakers set up in a properly treated room is that they can reveal a lot of stuff you would rather not know, they can ruin your favorite songs etc. especially if you learn how to listen critically, turning that mode off in your brain is tough sometimes.

https://www.rtings.com/headphones/reviews/beyerdynamic/dt-770-pro

https://www.rtings.com/headphones/reviews/logitech/g-pro-x-gaming-headset

If you go into sound profile graphs and compare the 770 to the Pro X you will find a nice bump around mid and high bass. If you look at where male voice lives in the frequency chart you will see that the fundamentals are all the way from 100Hz up to almost 1kHz, a cool comparison to do would be to try using an EQ to match the response of DT770 to the one you are used to and see how they sound then. Or even better, get Sound ID app (probably paid) or Sonar Works for headphones (also not free but genuinely solid) or Equalizer APO (free, but you need to set it up) or something and use the EQ correction curve to make both of these headphones EQ responses as flat as possible and then compare them on the same setup, same files and same day. A-B testing, with matched settings, is one of the best ways to compare any product.

http://2.bp.blogspot.com/_hwnCNuE0Gqk/TUs7ODXE9lI/AAAAAAAAAKA/hvdGzxRHlIc/s1600/Interactive-Frequency-Chart.png