As long as the TV is connected to the power, there is an audible hissing sound from the speakers (the satellites). The hiss volume is depended on the main volume of the speakers . If I connect headphones to the TV , there is no hiss. If I connect other devices to the speakers (mp3 player, PVR) there is no hiss. Turn on the A/V receiver. If the issue is not resolved, turn off the A/V receiver. Disconnect all the A/V cables from the A/V receiver. Turn on the A/V receiver. If the buzzing or humming sound is not heard, connect the A/V cables for each component back into the A/V receiver one at a time to determine which component is causing the issue.