Situation with a set of wireless outdoor speakers

Greetings. I am seeking some suggestion to assist me install a cordless speaker kit. I’m sorry just in case I am not within the appropriate thread. The issue is due to the wireless speaker system transmitter that I am utilizing for my surround loudspeakers. The transmitter won’t go into standby whenever my AV receiver is powered down as my receiver will always give off a humming sound. The main problem is that my speakers will keep sending out exactly the same sort of humming noise while the AV receiver is in standby. Curiously there isn’t a hum received from my receiver when it is on. I do not think that it is a ground loop issue. I’d personally be thankful in case anybody could offer a few recommendations in order to deal with this problem.