This TubeDAC is custom built from a kit, used about 1 year, and includes 2 good / tested Amperex made in Holland 6DJ8 tubes (those alone cost over $60).
Special lighting allows for determining it's modes of operation (see pic).
Diodes have been upgraded to fast / soft recovery ones to bring it closer to the 'TubeDAC+' version in sound, and the upgraded tubes have taken it to yet another level.
Note: there is no power switch to elminate any switches from the signal path. The unit was always plugged into a power filter which provided switching on/off. This reduced the number of on/off cycles on the tubes and circuit.