*Added this: Last few weeks I've had the hum.* Sigh . Read everything on TB I could find. Conducted a test tonight, just my gear turned on in our space and it was beautifully silent. Wiggled and moved and changed directions and could not reproduce. Turned on every electrical thing in the barn. Guitarist's tube Marshall hums but not my LH1000. What am I to conclude? Other use of electric from nearby houses affects my juice?