Hesitant to go for the Focal’s as I’m not liking the quality control issues. If I can find them used they usually seem to go for around $400 US (if they will even ship up here?), not too sure if I want to buy them used or just wait for a sale.
I’d be more inclined to agree more with @rmsanger. You could also get them here, open-box for $790:
Other fairly solid choices, assuming the DH590 will power them, are the Hifiman Ed XS or Ananda Stealth for $500 and $700 USD. You could pick up a HE6se V2 when it goes on sale, but I’m going to assume that you’d need a change in amp for that.
For bass I would go with Neumann’s and or the Focals but you should know that the Focals lack a little in sub bass, another option is Denon’s or Hifiman HE-R9 are good. Meze 99 wouldn’t be too bad but apparently the treble is spicy for some folks. Last rec. is maybe Beyerdynamic t5 3rd gen but you will have to look into those.
another question is Are you looking for something more “relaxed” or “exciting”.
In terms of relaxed the Harmonicdyne Zeus is smooth sound with a very wide sound stage, that i would generally categorize “relaxed”
On the other hand you have Focal elex or even the Elegia are much more clear, with a lot of energy - more on the “exciting” end of the spectrum.
A good all around is the Hifiman Edition Xs in terms of sound with no real weaknesses (its not perfect, and some headphone are better in certain areas but its solid in every category).
That being said it has its flaws, like a lot of planars it likes power so you need an amp with some juice (nothing crazy but still).
Also some folk dont like the headband (i dont as well but ive gotten used to it so i dont mind)
For a neutral sound signature, I’d go for Sundara, you can find a used one fairly easily and at lower cost. There’s also Edition XS, a bit brighter but has better soundstage, detail and layering. IMO best Open back in it’s price and beyond until you get to 1000 USD Headphones, that is if you are not too sensitive to some upper frequency energy.
Another rec would be Meze 99 Classic/Neo. I read 99 Classic has spicy treble on some reviews but personally don’t hear it, 99 Neo apparently is a bit more bassy and smoother so that’s another option. 99C is opposite of accurate, sounds fun and is very comfortable to wear.
@airmaster have you tried the HE-R9? I’m considering getting it.