I was starting to figure out the circuitry from the close-up photos, but decide that there had to be an simpler, easier method
I then performed a little Internet Sleuthing, and, as Paul Harvey would say, here is the rest of the story:
http://classmate.glmed.com/fff/6md8/6md81.jpgWhen you expand it (click +) it gives a large size schematic.
From what I found on the DIYAudio website, B+ voltage is approx. 285VDC,output power 6W per channel. Cathode current 12.8V / 510 ohms, approx. 25.1 mA per 6MD8, so they are being run fairly gently, at about 7W total PD per tube. No NFB loop.
http://www.diyaudio.com/forums/tubes-va ... e-amp.html