The Inspector

I also got mine from Costco last week but noticed there's a low humming noise coming from the subwoofer box when the power is ON. And it doesn't matter whether you have volume turn up or down, or if you have speakers connected, or if you connected to an audio source. If you put your ear next to the subwoofer, you will hear it constantly humming. I know there are multiple versions of Promedia 2.1 out there. Mine is latest version (no power switch, white LED on speaker, control pod has DB-9 connector to subwoofer). Does anyone experiencing this?

I just bought mine from Costco last week and got the same problem. Low humming noise coming from subwoofer box. I can't tell whether it's from the sub or from the transformer/circuit inside the box. But it's definitely noticeable if you put your ear on the box or 1 to 2 ft. away from it. Also tried at different electrical outlet and isolated from other electrical/magnetic interference, with or without L/R speakers connected, with or without audio input source. All resulted in humming noise from the subwoofer box. I am currently using a Logitech Z623 (2.1 system) but it doesn't have this problem. No humming at all.