Here are some of the reviews from Costco's website on the Klipsch R-12SW Reference Powered Subwoofer:
Got it from Costco online and loved it very much. After turning off AV, the humming noise was expected to stop after a few minutes and it did. Unfortunately, the humming noise lasted longer and longer each day. In less than a week, the humming noise did not stop. Tried switching it to off and unplug the power core several times. No help. The humming noise came back non-stop in either auto or on position. Had to return it to the store.
The speaker sounds great but has a loud hum when not in use.
