I run them a bit low bias, 1.4v right now. The pots are little twitchy, but they tend to hold a setting pretty well.
Just loosened the transformer base screws and tightened the bell screws then tightened the bases, same hum. Doesn't seem to matter which way the non-polarised plugs are inserted as far as hum. I have felt feet on the little bumps.
Very low hum from my speakers, they are 89db, have to put my ear up to them at idle to hear it. But the amps themselves are humming away. Power here is 124.5vac today, which is high average.
Any suggestions for what to look into? Thanks for any help.