Tube Driver Clone - Hum

[Clint Eastwood]

No mods to build instructions except I top mounted the power jack instead of on side ... wondering if this is issue now because it results in much longer wire run which passes many component. Will probably remove the jack and pull wires around to outside enclosure to see if any effect on the bypassed hum.

Definitely try that, the whole point of having a separate PCB for the power supply is to keep mains cycle stuff as far away from signal as possible.

That's also why I said that there was no DC ground reference to chassis. Which is defo part of your problem. The entire thing is basically unshielded!

If you look at the picture in the build doc from post 1, there is a ground wire from the output jack to an O ring that connects with the enclosure at the power socket nut. 
However, I do not see this wire in the picture of Pedalbob's version. I suppose it woud be best to exactly follow the original instructions?
In the original build doc, there is also a ground wire going from output socket to one leg of the volume pot, and then soldered to the housing of that pot. Now I wonder what is going on there, since that pot is connected to the enclosure is the housing of the pot and therefore ground not also connected to the enclosure there?