Elizabeth...My ACE515 has a sequencing system that kicks in when you hit the front switch turning on the preamp circuits (and anything else in those non-power amp outlets) first, and waits 10 seconds before powering up the amp plugs, which is sort of a main point of the thing...that and filtering. When switched off, it turns the amp plugs off immediately and the other stuff 30 seconds later. Of the 2 cords on it, one is a 3 prong main cable and the other is a 2 prong "switching" cable to allow it be be activitated by the switched plug in some preamps (like Adcom preamps).