If you built like i did the excellent phono preamp with a wood base and a metal top , you have to ground your power transformer to your star ground main point in the circuit board.
I've dismentle the bells on the primary side of it , and i found that the electrostatic shield is there, but connected to the left lower side of the primary with a ground lug terminal.
If you built a metal chassis, make sure that there's a good contact for making the proper electrostatic shielding fonction.
I had at first turn on, a good hum, so i connected the XFO to ground, and now it is dead silent, just the tubes noises.....
I left a picture in my personnal gallery for everybody view.
