Just received my Servo-15 a couple of days ago. On plugging it in (it has a 2 wire AC cord) with no other inputs I heard a 'hum' coming from the Amp module which I could hear from 3 - 4 feet away. I moved the Sub (90 pounds worth...) around the house to 3 separate circuits and the hum was evident in all of them. At that point I called the Dealer who immediately and with no questions asked sent their truck to come and get the unit. Brought another new unit home which we had opened in the store and plugged in (no hum). When I plugged it in at home, the hum is there - this is still without attaching the sub to anything other than AC. Damn, house problem. Borrowed a Monster 2500 Clean power from a neighbor (I know Chu, clean what?? but it was there) and it made absolutely no difference. Since then I have tried 2 other circuits, unplugged the refrigerator and any halogen or 'cheap' lights. I went as far as turning off everything in the house but the sub and the hum is there. My Main Panel is 40 years old but has good NMD 14-2 wiring with a 6 ga ground wire strapped (bonded) to both the water pipes (metal) and an 8 foot ground rod outside the house. I had previously checked all the plugs in the house for proper ground and wiring with a tester as I had to replace all the 2 wire receptacles with 3 wire when I moved in. All of the boxes (and plugs) are properly grounded and wired hot/neutral OK. Since the sub is 2 wire, this is not a ground loop problem but 'noise', either RF or EMI on the line IMO. What are some of the things I could check further, and what options do I have. I own the house, but will be selling it, so a whole house solution might be too cost prohibitive. Note that the hum does NOT come through the speaker, it is in the amp itself, so when it is in the corner of the room away from the listening area it cannot be heard. I just 'know' it is there so it annoys me..... I have emailed Paradigm for their opinion but it is the long weekend here and I would expect them to reply after Tuesday.