Vacuum Tube D3A Parafeed Headphone Amplifier
Includes NOS and matched Valvo D3A tubes.

The D3A tubes are loaded with a cascode DN2540 CCS.
The DN2540 mosfets were matched so that both tubes draw identical current.

Works equally well with low and high impedance headphones.
Initially used LED bias but it didn't measure very clean so I switched to an unbypassed resistor.

This is one of my cleanest builds using the highest quality parts.
* Custom powder-coated aluminum chassis in Air Force Blue.
* Sowter 8655 mumetal output transformers.
* Switchable HiZ / LoZ (Tocos silver-plated 4DPT switch)
* Furutech RCA inputs
* TKD 2CP-2511 volume potentiometer
* Mundorf EVO 4.7uF output caps
* CLC power supply with Hammond 157H 10H choke (220uF caps)
* NOS Cinch ceramic sockets

This amplifier is somewhat inspired by the Bottlehead Mainline and Papa Rusa headphone amplifiers, with a few key differences.
https://wtfamps.com/papa-rusa-headphone-amplifier/

Asking $1000 shipped, please feel free to ask any questions.
Thanks for looking