XLR out on a tuner?

@n80. Weird. 

Not so weird.  Probably only a transformer that needs either securing or tightening of the leaves.  Open up the cabinet.  If the transformer has bolts going through from one side to the other, tighten them.  Also, look to be sure that the transformer is tightly bolted to the chassis. Ideally it will be supported by some rubber-y footers.  Tightening everything up will likely rid you of the problem.  This thing is old, is it not?  Why are you so quick to dump on it, when in fact this is a typical problem that can apply to almost any vintage gear?  It may even be that someone tried to service it and left the transformer loose in the chassis.  If the two suggested cures do not work, you might be able to dampen the vibration by adding a weight on top of the transformer.

I have no plans to dump it. I said above that the problem was not bad enough for me to send it back.

But thanks for the advice, I will do just as you suggest and take a look. Certainly can't hurt. And if all else fails I think I can simply set something on it and stop the hum. Even that is probably not necessary since I can not hear it from 12 feet away anyhow.

I do not know how old it is but definitely not vintage. Denon does not make it anymore but there appear to be some places out there where you can still buy one new, usually shown as special order, so who knows. Anyway, not real old.