Though a good thought, I'm just going with the old cliche explanation for "Its magic".Ok... so where does the electricity come from? Are the instruments from the future? Is there some sort of time vortex? A giant hamster wheel generating power? (Complete with giant hamsters?)
What other entertainment is available for the crowds? How about an evil marionetteer, with life size marionettes that also play instruments?
If you steampunk things up, it could offer a lot of opportunity for improvisation.