I own a AM 10 Series V for 3 years.
The system is always powered on. Is that OK?
Sometimes (and I cannot clearly identify when or why, random) the subwoofer starts to hum. It only happens when the receiver is off. The hum noise volume is not always at the same level. I noticed that sometimes it happens when I open the door and wind enter to the room, but also happens without any event.
In order to fix momentary the problem I have to touch/move the LFE / Bass controls (sometimes the sound volume moves while touching these keys, and it is not always easy cancel). In the worse cases I had to unplug the power cord.
I also reversed the power wires, but there was no change.
I assume it is not a ground loop because it happened while AVR is power off and it is not a permanent sound, it starts random. Both units, the AVR and the speaker system are powered by power transformer.
Any suggestion that can help are welcome.