I had the some problem hum in right channel. Changed tubes, moved speakers, always in right channel. I did not have that problem in previous apartment, Supratek was dead quiet. But since I have moved, hum is constant.
It is mains, power cables related. Recently I have bought umbilical cord from Brat. I was really angry that it took him so long. But to be honest hum is gone first in 2 years. I still cannot believe it. Neither power cables not interconnects did that much of a difference for me. Dynamic is better, micro dynamic is better too. I doubt that in previous place they would be such a difference but for peoples with hum problem it is a great buy.
It is mains, power cables related. Recently I have bought umbilical cord from Brat. I was really angry that it took him so long. But to be honest hum is gone first in 2 years. I still cannot believe it. Neither power cables not interconnects did that much of a difference for me. Dynamic is better, micro dynamic is better too. I doubt that in previous place they would be such a difference but for peoples with hum problem it is a great buy.