Hi,

Best is to adjust this to have the same voltage to ground on what is labelledTP3 (Test Point 3). I'd be tempted to just stick 33k across it and see if I can use VR4 to adjust the rest of the difference.

BTW, try the 12AU7 without the cathode capacitor restored, you may find it reduces noise enough to not need to put the capacitor back at all.

Ciao T