The one I had hummed loudly used with a balanced power unit I was trialling. From your description however it doesn't seem that any power conditioning is being used.

Main system: NUC, Roon, Network Acoustics Ag ENO/cable, 218, 5200SE, Townsend Podium, Sennheiser HD820/800s, Sennheiser HDVA 820 amp.
Mobile: Explorer, IE800
Kitchen: MS200, F80