Clean channel hum?

[Nebulozny]

My MA has recently began to hum/hiss pretty loud on the clean channel, drive channel is dead silent. Before this started clean channel was really silent, no hum at all.
Could this be preamp tubes, I changed them to Tung-sols like 3 months ago? And which one is for clean channel, or are they all in the circuit when clean channel is on so I could do some swapping?

[Phano36]

Did you checked if one of the tubes pins was not crooked or bent ?
Put back your old tubes, maybe something is wrong with your new tubes. It will give you some indications.
Check the sockets solder points, maybe one solder point is crack ? I saw that before in my Fender Deluxe