I have a pair of Hifiman Sundara closed backs (see profile pic).
The overall sound as is, is just mweh. Not existing.
There are a number of sources out there for various PEQ & GEQ settings.
I’ve tried all the ones on here:
I just didn’t find any, to me, that made me go ooow, wow!
I then came across this on ASR:
The simple 3 band PEQ is a little tweak in the right direction. Better tonal balance across all frequencies.
Don’t settle, that’s my thoughts for headphones. Tweak away.
Maybe a different set of Headphones if they are not working for you?
These aren’t perfect, however the tweaks make them better. My ears are fairly easy to please I guess.
At the moment my house extension and SWMBO is stopping that little venture. I’m eyeing up some Focal and/or Meze cans.
Just wanted to share.
I compared the Focal, Sundara and Meze cans side by side and none of them did anything for me. I am using Audeze LCD-XC at the moment. At the recent show I went to, I loved some of the Stax kit I listened to as well as the bizarre but great sounding RAAL - SR1b and paired AMP. But, at the end of the day, I need Closed back for a number of reasons, not the least of which in marital peace.
I’ll have to sell a kidney for the RAAL SR1B’s. Fantastic looking.
Alas, my budget will not be as extravagant as the Audeze either.
I’m hoping I’ll be working in London in August for CanJam. 
Appreciate the input @Rugby , now if you wish to send your Audeze to @AceRimmer I’ll collect them next month when I’m in Florida 