#1
I was playing a gig tonight and was getting noise interference when ever I would click any kind of boost whether it was from a tube Screamer, GE-7, or compressor. The same thing happens when I practice guitar at the computer, I will hear something click on through the amp(like someone turned a light on or something) and then I will get this hum through the guitar. It will only stop if I hold the guitar in certain areas of the room.
MARTY FRIEDMAN--"It’s a lot easier to be technical than it is stylized; it really is... But I think it’s a lot more rare to have someone who’s really got their own sound because that’s something you can’t practice."
#2
It will be the UV lighting at the venue and from your PC monitor/ other electrical gadgets

Only way to get rid of it is to gate until it goes