amp noise

Hello guys. Recently I noticed that both my bass amps ( PG spark and katana) make a buzzing noise (when no touching the strings). The noise seems to disappear when I plug them in different places (When at a friend's house for example). Is it possible that my house electric wiring is causing...

Okay here's a Paul Stanley Video with some amp noise(Hum). I am very curious to know what it is. Possible causes. etc.... Thanks, FH

My Mark Bass Mini CMD 121 P is starting to make a slight distorted/rattle type sound on certain frequencies. I've only recently started to notice this. At first I thought it was my bass making a slight rattling sound so I checked on all 8 of my basses and it happens on all. Any ideas as to...