Answer your own question with an $8 receptacle tester. Then make sure that the green wire is attached on both ends.
Grounding questions
I’ve had an issue with a slight hum through my system for a long time. System consists of Jolida Fusion Preamp and JD1000P amplifier. Both plugged into Futman Elite 15 power conditioner. It’s not dependent on any sources. Hum is there when amp is on.
I have a dedicated line for the outlet to the Furman. Hum does not increase with higher volume.
Maybe it’s an issue with the power amp but it could be an issue with the house wiring. The house is 62 years old and the fuse box is original and not grounded. Before I pay $800 to have it grounded, what do you think is causing the hum? It’s not cable related as I’ve swapped interconnects. The pre and amp are connected by a balanced cord.