I should add, that certain interconnects have a tendency to pick up hums more than others (on my system).
I was chasing hums on my system for ages. In the end I ,,,,
- found and replaced some microphonic tubes in my m3
- replaced Aurealis Ic's with others I had on hand
- changed my eastern electric phono stage to 834p
I'm pretty good now, with those 3 things. Worth playing around with the first 2 points.
The only issue I have left, is a very small amount of transformer hum, when the radford has been running for 2+ hours (ear against driver detectable level). Don't think I'll ever fix that. But that's ok, it's fine, given the other hum improvements.
I know your pain man.