Anode Acoustics Headphone Amplifier No 4. Solidly built, plenty of clean Class A power, neutral and balanced sound. Comes with the pictured volume knob as well as the stock silver one. These are made by an Indian company, but this particular unit has a built in 120V (US) linear power supply. I bought it new in July 2021.


http://anodeacoustics.in/index.php/headphone-amplifier-4/