Trying headphones again… ZMF or Abyss?

I use  Meier crossfeed and LLC  component of Foobar 2000 and the trifield component with success with my speakers system and my secondary headphone (sextett)...

I  am also happy with the vintage AKG K340 as my primary system ... But it is hard to optimize it righfully... Once done we had imaging out of this world common to almost all headphone and a speaker like sound...

The price for it is low cost anyway and  because most people believe new is better, the pricier it is the better it is, no one want an old complicated headphone...

Here the patent about the AKG K340 and the reason why he exceed any headphone i listened too ...( i could not used the microzotl two to drive it properly though  i use my SAnsui alpha headphone out but the LTA microzotl level 3 preamp  is more powerful i think and could do it) :

https://patentimages.storage.googleapis.com/d1/a4/49/920c561c913899/US4005278.pdf

There is a trade-off between details for details and spatial qualities of sound, The K340 hybrid took a very good compromise between these two goals.because it is a complex headphone to design and hard to sell it was never optimized and recreated in a new improved state and AKG goes to another road. AKG K1000 was the next legendary flagship...

I’m not familiar with either headphones, but I was looking for very similar qualities as you when building my headphone system so thought I’d chime in.  I ended up with Hifiman Arya Stealth headphones as they are neutral, open, transparent, and provide an expansive and dimensional soundstage and imaging.  Also, I find their design to be very comfortable and light, and I can wear them comfortably for hours unlike some Audeze headphones I tried.  In your price range their HE1000 Unveiled phones ($2699) are a significant step up from my Aryas that I’m quite happy with and are very similar in size/weight so should offer similar comfort levels.  Here’s a review that goes into some detail about their sound characteristics but also compares them to the $3500 ZMF Calderas and found the HE1000’s soundstage in particular to be more expansive so thought you’d find it interesting.

https://www.headfonia.com/hifiman-he1000-unveiled-review/

Here’s another review that’s also very positive and goes into a little more about the strengths of imaging/soundstage among other things.

https://headfonics.com/hifiman-he1000-unveiled-review/

One limitation is they come with a balanced connector and don’t include a 4.4mm adapter, but I imagine there’s an easy solution to that or you could buy a different headphone cable but just wanted to mention it.  Hope this helps, and best of luck. 

@sfpeloton 

I agree with Soix regarding the HE1000 unveiled. To throw one more headphone into the mix (because this is an A'gon discussions feature); try the Meze Poet because its imaging/soundstage features are similar to the Hifiman, and are faster, and better constructed. I auditioned both at Audio46 and purchased the Poet. 

I have the Verite closed which I love and are very comfortable but not light, the Verite uses wood cups so they are a bit heavier. If you are looking for a closed back see about a used pair of Focal Stelia, I have a pair that I swap out with the ZMF. For open back, I really love my Meza Elite, light, expensive sound, detailed, and warm. Used you can probably find a pair in your price range. I also have a pair of Sony ZMR closed back headphones, they are light and can be found well within your price range. Good luck in your search, I went down the rabbit hole during Covid.

I highly recommend investing in a better headphone amp. I have at least five different pair of flagship headphones. Including Sennheiser HD800. All the different headphones sounded different with different strengths and weaknesses. Then I got a truly great headphone amp the Woo WE5 and then put Takatsuki 300B tubes in it. OMG. For the first time ever (after a dozen amps... over decades) the sound quality improved by and order of magnitude... then suddenly the Sennhieser HD800 quickly found there way to the very top of my play list. The Focal Utopia, and Denon, Ultrasound, Beyerdynamic... just fell into disuse. The difference was incredible. I only use the HD800’s now, often for an hour or more a day.

Very often preamp headphone output is a second thought and even on incredibly expensive preamps is not very good. 

You can see my system under my USRID in Virtual System. But for decades I tried to make my headphone system as satisfying as possible... I imported a high current amp from Germany... etc, constantly tried new top of the line headphones. It was the head amp from Woo that finally made my headphone system as satisfying as my main system I can listen for hours... the physicality of the bass... the delicacy of the violins or voices. The Sennheisers are world class. 

Over time I found a headphone system is like a main system. The headphones probably will cost less than your main system speakers. The electronics cost should be about 80% of your headphone system.