No, it isn't a short, there is voltage drop across the device. But one single led connected to the output will be smoked in no time, you will almost cetainly exceed the voltage rating of the led. This is why you need to using a dropping resistor or multiple leds. Do yourself a favor, don't hook up anything to the amp terminals without at least a 1-2 ohm resistor is series with it. This way, no matter what you do or screw up, your amp will never see anything it can't handle.... If you completely understand what is gong on here, feel free to hook a bunch of leds up inseries directly to the output, it will work just fine....