One of my tubes has developed a problem where it begins to cause static in the channel. Even with the volume all the way off there is a noticeable static coming through the speakers. I have swapped the tube and confirmed that static occurs on which ever side is using that tube. I had the same issue a few weeks back although it had seemed to settle down again and play without issue. I wanted to know if there might be something else to check or if its just a tube that's going bad and needing replacement.