Hello there, some support necessary to resolve a problem with a cordless speaker

My apologies should I be in the incorrect thread. I am trying to find some help regarding how to set up a cordless speaker. In order to avoid loudspeaker cable disorder, I had bought a 5.8 GHz cordless speaker system for my surround speakers. The transmitter connects to the surround receiver rear loudspeaker outputs. Generally the transmitter goes into standby after a couple of minutes of not having acquired audio. But, my AV receiver continues giving off a hum whilst in stand by. This stops the wireless transmitter from entering standby. Thus my rear loudspeakers will continue sending out this humming noise anytime I am not viewing television. I’d be thankful if any person might provide some recommendations in order to fix this challenge.