I picked up an old "Rogue" tube amp a friend was going to toss out. He thought it was a low power piece of garbage. I took it home and played through a 2x12 and noticed the tubes had all gone microphonic, as soon as you turned up the gain or the treble and bass pots you could hear it through the speakers. I changed out the preamp tubes with new 12AX7's and replaced the 2 6K6GT's with 6CA7's. I know they aren't the same tubes but the amp works and is loud as hell. Nothing blew up but I'm wondering what kind of damage I'm going to do to the amp if I was to leave it like this long term. I do get a lot of hum out of the amp but it gets quieter as you turn up the volume even without masking the noise with instrument signal. Any advice would be appreciated.