If you are interested in software-driven headphones, the Smyth Realiser series has always fascinated me.
https://www.cnet.com/news/smyth-realiser-a8-perfect-surround...
https://www.soundonsound.com/reviews/smyth-research-realiser...
https://www.cnet.com/news/smyth-realiser-a8-perfect-surround...
https://www.soundonsound.com/reviews/smyth-research-realiser...
0: https://github.com/Azrael3000/headphone-guide 1: https://www.head-fi.org/threads/my-diy-electrostatic-headpho...
For those who are interested in entry-level, non-DIY route
Drop (formerly Massdrop) has their variant of the classic Koss ESP/950 electrostatic headphones for around $500. They sold out earlier this year.
https://drop.com/buy/massdrop-x-koss-esp-95x-electrostatic-s...