Well a bit of an update on my copper tube adapter, each one of my 6DJ8's hum, the 6N23P or 6N2P not so much hum but there was a faint bit of tube rush in those. The Siemens 6DJ8 was the absolute worst the hum on it was exceptionally bad and would NOT go away.
So I build a test adapter with a little bit of Mogami Star Quad and a twisted pair of 18 AWG heater wires. I kept the heater wires away from the A/G/K wires as much as possible and all the hum is gone, even the tube rush from the Soviets. So I am going to have to re-engineer my tube adapter.
1) Heater wires brought outside through a hole in the bottom and top at the back of the adapter.
2) Run new heater wires in the pipe using shielded wire, attaching each end of the shield to the pipe.
3) Create a new adapter out of lexan, with the Tube rings removed so it is only as thick as an octal socket and plugs right in over top of the B7G sockets. (<- Leaning this way.)
So much fun we go through with this hobby, the BreadBoard option would most likely work the best but would not have the WAF where my amp is situated.
Here is the totally silent test adapter with a 6N23P installed and my new German Maestro GMP 8.300 D Professionals...