So, the very day I get two new pedals and an extra pedal power supply and my amp is buzzing like crazy. I try different guitars buzz still there. I systematically unplug and plug every single thing in home studio. Still buzzing. This took an hour or more easy. I take the amp in a different room. No buzz! What the heck. Back in the studio. Buzzing like crazy. By pure luck my wife turns off the kitchen lights downstairs and... buzz is gone! Despite the same dimmer switch being there for years, apparently a bulb is going bad and that was the maddening source of my awful buzz. Soon these lights will be replaced with LEDs and new dimmers, but my trouble shooting sequence was thrown completely off by the new gear. Perhaps this will help someone else. Always check those darn dimmer switches!