Yeah, the advantage of the SM unit is it has all sorts of frills like a mono switch, two volume pots, two inputs, two outputs, and a powered headphone output - but truthfully, none of that is really worth it to me seeing as how I only plan on having one set of monitors in the forseeable future, and my interface has a headphone out! (and I'm planning on eventually getting a FF400, but that has a headphone out as well)