That's true in many areas of physics, but acoustics and electronics (in audio frequencies, at least) are very well understood. To sustain a claim that unknown physics underpins the occasional claims of sound improvement due to elevated speaker wires would require not just evidence of unexplained electrical or acoustic phenomena, but verified evidence of unexplainable electrical or acoustic phenomena.
In other words, it would first require repeatable, verifiable evidence that elevating speaker wires consistently creates an audible change even when the listeners (and experimenters) don't know whether the wires are elevated or not, and then it would require that there be no known factor in physics to explain it.
I don't think we've reached the first point yet, of having repeatable and verifiable evidence that elevating speaker wires consistently creates an audible change even when the listeners don't know whether the wires are elevated or not.