How much hum is acceptable? My '63 B15 is humming like crazy. I've had it re-capped and all new tubes, hum balance adjusted and it still has an annoyingly loud 60hz hum. Two different techs have worked on it and so far no luck finding the source. I've owned a couple of these in the past and I don't remember them humming like this. Anyone have any ideas to share please help. (JimmyM ? ?) I want to use this amp in the studio this fall but it wont fly like this. Thanks, B.