I'll say it out loud- the microphonics are a result of unintended VHF oscillation from using a high gm tube. The cure is a grid stopper resistor, typically 1k, placed right at the grid pin.Can you drop me that note too please?
The 6DJ8 familay are great tubes but you have to be very careful with them since they want to work at RF whether you want them to or not.