Not only has the emerald more output, but it also is a bit more compressed, making it easier adaptable to higher gain playing, whereas the mule remains more open. Not to say that the EM is really compressed though. They both have the IV sweetness, but the Mule due to the lighter wind with a vintage wire actually is brighter and crisper. The modern wire of the EM smoothes things out a bit making for a fluid singing voice with an edge.
