Hi, Just upgrade to the P7 from Rotel RMB-1075 and RB-1080. I like this amp! Well made and sounds the business! I just want to ask fellow P7 owners if they hear hum from the transformers. I can hear a hum from about 3 feet away in a silent room. This buzz changes volume at different times of the day and is loudest when the Mrs' uses her hair straightenerss!! The hum is then audible from 8 feet away. Sound level meter can't pick it up so it is not THAT loud but still of concern. There is no noise from the speakers - purely a mechanical sound from within the amp. Any help would be sincerely appreciated.