@holmz - RE:
Should I wind a copper wire around the thing and attach it to the preamp ground as a test?
Wrap a wire round the neutral of one of the phono plugs and ground it at the outlet
BTW - it could be the souce and NOT the cable
- I had a DVD player that caused hum
- tried everything but still hummed
- grounding the neutral of an input on the amp fixed it
- the DVD player had an isolated (i.e. 2 pin) power supply
My Bluesound Node 2 causes a hum...
- i.e. IF, the phono stage (which is correctly grounded) is not connected to the system
Its a common fault with components that have any type of "isolated" power supply, like...
- battery powered components like tablets, phones etc..
- CD/DVD players with 2 pin power supplies
- (Some) Bluiesound products
- many other products like the bluesound
Hope that helps - Steve