Re: could it be a power issue?
You know abuot pickups hum (single coils)? Change guitar, guitar cord. Plug in to the outlet of the nearest electrical switchboard and put out from socket everything you can, or better go to a friend. It can be anything. Cold solder, worn tubes, broken ground inside. Some amplifiers have noise regulation. Theme for a technician. I have some noise with high gain and volume. This is normal.
Price of voltage conditioners starts from ~1000 $ everything below are power distributors with some filters - waste of money.