Tube Audio Design (Paul Grzybek) Tadac dac question


Does anyone out there know the DC voltage requirement for the late Paul Grzybek's Tadac tube dac? I own one and want to add a linear power suppy. 
pmboyd
Most wall warts are marked with their voltage output and whether they output AC or DC, but if not it could be easily measured with a basic meter.

It's the prototype. Ugly as sin but sweet sound. The same except it uses an outboard power supply.