seek advice on hum problem from phono preamp


My EAR 834P phono pre produces quite audible hum at the speakers. It is plugged into a Noisetrapper isolation transformer, which is plugged into another big NT isolation transformer. Probably not a ground loop: cheater plug on the EAR, or anywhere else, doesn't help. Using a Grado Statement Ref cartridge, which is unsheilded and was prone to hum pickup from the motor on a Rega TT, but isn't close to the motor on Thorens TD850; TT is far from the EAR. So the hum comes from the cartridge or the phono pre. Is this just typical of tube phono pre's (meaning, a SS unit is the only real solution), the EAR834P in particular or a defect in same? can the type of tube be a factor, do I need a different cartridge, or what? would greatly appreciate suggestions.
128x128lloydc
You haven't mentioned if this is a recent problem or one that's existed since you installed your phono pre. I was recently befuddled by a phono hum problem, couldn't figure out why it was happening. Then in a moment of Homer Simpson "Duuuhh" clarity, I remembered I'd changed interconnects and that's when the problem started. The unshielded interconnnects were the problem, replaced them with shielded cables and the problem vanished.
I have very laud hum from my new modwright ph9 phono stage even when my volume is set to zero, my old phono stage is a ear 834p no hum whatsoever, my amp is ear v20, I have set the power supply as far as it will go from the phono stage but still the same laud hum, my turntable is transrotor with SME309 and PARADOX PULSE MC, I had no hum problems with this system using the ear 834p.