Choosing Headphones up to 1700 USD

I am really into headphones now.

I have the following amps for headphones:

- Benchmark HPA4 (incredible for both 2 channel and headphones)
- Topping A90 (very good overall and great for $500)
- CODA Csib integrated amp (being shipped and to be used with RAAL SR1a headphones)

I think the Topping A90 is a great amp and should drive most $1700 headphones. You may want to look at the under the UnderwoodHiFi of the rebranded Russsian headphones + Topping A90 = $1700

https://www.underwoodhifi.com/products/lsa-headphones

My other headphone is the Meze Empy. A much different sound than the RAAL SR1a. Enjoy both a lot.

I think the HIFIMAN ‘phones would really be worth a try given what you’re saying. What I find really striking about them is their expansive “out of the head” soundstage and the very detailed yet not harsh or fatiguing treble. The bass is different in that it has a lot of impact and is also exceedingly quick, but it may not have the lower end depth or heft you may have heard from ‘phones that overemphasize that area or excel at the Stygian depths. But you may find the bass more than sufficient, and when combined with the other considerable strengths the planars offer you may be more than happy with any trade offs.

So, what would I recommend? You can get the Arya open box from HIFIMAN for $1300 as I think that gets you well into the best of what planar technology can deliver. The Aryas will, however, require a decent amp, and I agree with others that you need an amp anyway as I think it’ll also significantly improve what you’re hearing out of the DT1990s. I’m not familiar with your Scarlett at all, but I’d consider something like the Singxer SDA-2 amp/DAC as it’s fully balanced, offers six filters to customize the sound to your liking, has plenty of power, can be had for about $600 and uses one of the top AKM DAC chips that will provide lots of detail but help avoid harshness and glare versus some other options. If the Arya and SDA-2 are too much for your budget the Anandas are on sale for $699 and would also be great, but if you can stretch for the Aryas I think it’s very worth it. Incidentally, I’m not sure the Audeze would be the best choice for you given you’re coming from the very detailed and transparent DT1990s as you may find they skew a bit too far in the other direction of being on the softer/warmer side of things — but I could be wrong.

Sorry to drone on, but hearing a good planar headphone was a revelation for me and thought it might be for you as well given what you value and are looking for. Hope this helps at least a little, and best of luck in your search.

@soix thanks for the very informative response!
The Scarlett is a studio USB interface used for music production (it's basically a DAC/amp unit but suited more for recording and monitoring rather than audiophile listening). 
I decided to start with a DAC/amp and to save for a while and than get headphones (maybe indeed Arya). 
What do you think about this DAC/amp?
https://www.monoprice.com/product?p_id=24459
I heard about it in this review:
https://www.youtube.com/watch?v=8KiXpt97wf8&t=1s
and also here:
https://headfonics.com/monoprice-monolith-thx-amplifier-dac-review/

I think the Monoprice is probably a very good unit and a good value (gotta love Monoprice!).  The SDA-2 uses a more advanced AKM chip and they’ve paid a lot of attention to improving the USB input, clock, jitter, etc. whereas I don’t see anything about this implementation on the Monolith, which is a little frustrating as this is fairly important.  Just going by what I’ve read, your DT1990s are already on the transparent/detailed side of the sonic spectrum as is the Monolith, so I’d be a little concerned that the two together may be a little much and possibly become fatiguing over time.  The SDA-2 on the other hand will still give you a lot of detail and transparency with perhaps a little more flesh on the bone in terms of tonality and heft and maybe a little smoother and more refined sounding, which is why I thought it might synergize well in your particular situation.  I think both units are great and excellent values, but as with everything in audio it ultimately comes down to personal preference and system synergy so let that be your final guide.  In searching around I did find a review from headphones.com that actually compares the two and this is what he had to say.  I have no idea about this guy so can’t vouch for the validity of his impressions, so FWIW...

Well, I think these two are approaching AIO from different perspectives. The THX feels wider and cleaner. Separation feels slightly better. More fatiguing treble, and overall not as enjoyable as the Singxer. It feels more “harsh” to me. That being said the THX-788 is still my recommendation for AIO or even DAC/amp under $600, and honestly even higher depending on your preference. The THX-788 is a more analytical sound and it has EQ options (a little hard to figure out at first but once you do it is pretty easy to get around the menu). If you are looking for the best bang for your buck, I would go with the THX-788. If you want a more relaxing involving sound and don’t mind not having EQ options baked in and don’t mind the price, or will be potentially pairing with better amps down the road, Singxer SDA-2 is the option I would go with.

Again, hope this helps and by all means let us know what you find and decide. 

Does anyone have an opinion on electrostatic headphone amps?

I wanted to get something that sounds warmer, richer rather than accentuate the hyper detailing of the headphones.

I was thinking of Woo GES, but read mixed reviews about the circuitry.