I'm still working on this amp, it's all pretty much working except for the phono preamp. It's modeled after the Marantz 7, using 6N2Ps and a 6N3P. I had a bit too much gain, and too much hum, so I put in a bit of local feedback on the second amplifier. With that feedback in, I have about 3mVPP of hum out of the preamp. I am happy with that. Without the feedback and the phono hooked up, I'm getting 20mVPP of hum out of the preamp. The hum about drops in half with the phono disconnected from the amp, AC connected to the phono does not matter, and the ground wire is connected. The phono is a Techniques SL-BD22.
The preamp does work, and Eddie Howard sounds fine, but it hums between songs.
So no phono connected and feedback = 3mVPP
No phono connected and no feedback = 20mVPP
Phono connected and feedback = 20mVPP
Phono connected and no feedback = 30MvPP