Thought this link might be of interest:
https://www.janszenaudio.com/headphones

 Unfortunately, I have not heard electrostatic phones before. It would be great to have a try with them.
On a related subject, did I hear of some new (no really, something not tried before) headphone driver? Sorry that I cannot remember more, but i believe that it was in 'the voice coil' magazine. So much of the personal stereo (phones, earbuds and the like) have spawned some good ideas.
Now if only they come up with reasonably priced and great hearing aid technology...