Low Static Buzz Issue

I have a Peavey Valveking 100 head that I believe is giving me some problems. I was playing through it earlier today at a friend's house and everything sounded fine (no noise). Then I brought it home and played through it for a bit and it still sounded good. Then just a little while ago i turned it on and noticed a low hum along with a static noise that wasn't there before. The hum and static gets louder the higher i turn the volume. I plug in my noise suppressor and it does nothing to decrease the noise so I'm pretty sure it's not the guitar. I've switched out the cables so I know it's not them. Also, the cab (Orange ppc 212) is brand new so I'm pretty sure that's not the problem either. Could it just be a blown fuse or maybe a faulty tube? All of the power amp tubes still light up when I turn the amp on. Could it somehow be an issue with the power outlet I'm plugged into (even though it was working fine earlier today)? Any help would be great. Thanks.

Low Static Buzz Issue