Ok so i put in my new tubes. When i first started it all up, the sound was fine and i had a much more 'fuller' tone. I turned it off, put the poweramp back into the rack case and i get this hum. I can still get sound out of it, but i get an annoying amount of hum when i stop playing. Now there's nothing in the room or downstairs that can interfere with the signal so it must be something else. Any one help?
