Help please

Hi,
I've had my mini recifier for almost a year now and I've notched some strange noises ( cracking popping etc ) on both the clean and dirty channel. Not very loudly but wasn't their before. Also on the 10 watt clean settings their a loud hum even when playing. Also the tone doesn't sound like it use to. Also when it's on standby it's fine.
So is the early symptoms of a bad tube? Is it the pre amp tube or the power amp?
got a big gig in a week!
Thanks

I'd bet it's tubes. You can fish around, starting with tubes that are common to both channels.

If it were me and I had a gig coming up, I'd replace them all and then work out which tubes work OK after.