If you are getting a low frequency buzz or hum then this points to poor grounding. This is quite common where Cat cables have been used, particularly if some of the adapters or connectors are not suitably shielded. I suggest trying a direct cable connection from the Theatre to each speaker to give the best chance of a good connection, you can see suitable cables here:-
https://soundsheavenly.com/43-powerlink-rj45-cat5-connection-models-from-2013
Kind regards, Steve.
Location: The cable workshop, England
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