We've got a new design of the hybrid high-end class A headphone amplifier. It's not live-tested yet - although it's in the pipeline for prototyping and testing, it will take time - we are busy with the other projects now.
If somebody is interested to build the head-amp, test it and share the results - please let me know. I will share the schematics and gerbers and provide full support for the build.
The tube is 6DJ8. The MOSFETs in SE class A OPS are IRF610 (require the heatsinks).