Ben, this lower setting does not optimize the receiver for handling the speakers with a lower impedance rating, as some imagine. This is basically a safety-related measure intended to limit the possibility of overheating, pursuant to UL requirements. This limits the voltage which is available on the power supply rails. When following Ohm's Law, when voltage goes down, so does current and power. Yes, this will reduce the possibility of overheating, but does it at the expense of maximum performance.
___________"Don't worry about the future, it is already tomorrow in Australia..."My Website