Hello,
I have two 17" studio displays. One hums when it's cranked all the way up, but
when I back it off just a bit it stops - just like yours. The other is the opposite...
If it's not up all the way it buzzes, though it's more faint. This is undoubtably
a voltage converter, probably for the lamp. These all seem to buzz, no matter
what they are in. I just leave them in a position where it doesn't buzz and I'm happy.
Of course, I probably never would have noticed if I weren't using them with
cubes. I would say this is kind of normal and don't worry about it.
-Ph.D.