Usually, when I do my recordings, I either record electric guitar directly, or I go accoustic through a micophone. After my exposure to actual studio life and recording techniques, I learned that the proper way to record electric guitar is through an ampifier, and then into a microphone (because it gives better tone than straight into the computer via amp). But then I noticed something very weird. In there is a humming coming through my amplifier. Yes, I know that is common with many cheap amps, but mine is a 600$ amp.

My question to you is, what could be causing this 'white noise'?
Electrical power boxes?
TV's?
Closeness to computers/radios?

Any suggestions?


PS. this is the amp.
(Behringer GX210)