This could be interesting:
90mm Open Planar Magnetic Headphones FT5
Planar magnetic drivers are in between dynamic and electrostatic headphones. Like dynamic headphones, there is a sort of coil on the planar driver. Similar to electrostatic headphones, the diaphragm is a special kind of thin, micron-level film. The FT5 is 28nm chip-scale processed, leading to an...
www.fiio.com