What happens if you plug them with the wires energized? When you plug the first and then the second.. I don't think this should be done, but given how some people operate their mines...
Next experiment; Would it turn on if you used two 120v from different phases (would it get the 208v from the two hots?). Theoretically speaking, of course, don't try this at home, in the name of science.
I had an Italian stereo amp it could do that use two 120 volt circuits from separate legs of a USA circuit box ..
Back in the 90s maybe I could find a link to either speaker builder or stereophile.