A problem developed with my Ampsandsound Stereo 15 tonight. When I started it for the first time since last weekend, there was now a noticable feedback buzz instead of the usual dead silence. As i approached the unit, I discovered that the feedback became louder when I moved my hand towards the 12AX7 position. As I moved my hand back and fourth from the 12ax7 I could control the "volume" of the feedback. So, I powered down the unit and replaced it with another 12ax7. It also exhibited the same behavior. I don't believe this is any sort of ground issue, as it was perfect for nearly half a year before today.
Anyone have any ideas?