Ploopy Open-Back Planar Magnetic Headphones @ TechPowerUp
 

The Ploopy headphones are a love letter to open-source design. Not only featuring customizable hardware you can download the files of and 3D print yourself, Ploopy also offers a DIY kit or a fully assembled version depending on your preference. There is also open-source firmware loaded on a DAC/amp board with full EQ support!

https://www.techpowerup.com/review/p...ic-headphones/