I guess it’s all a bit of trial and error. I have a set of SME rca cables lying around with ground cables with spades at both ends which means four trials, one with no ground cable attached, one with one end attached, one with the other and one with both!No that's not the test. A simple shielded silver cable can work, but the phono cable includes the ground wire with spade connectors. I eventually found that disconnecting the ground cable between the SUT and the phono worked best in my system. Hum is usually a ground potential bugaboo in the system, if your cables are shielded.