Eric, welcome to Axiom. Despite any suggestions to the contrary in the owners manual or elsewhere, never set the receiver to the lower impedance setting. Leave it at the default. The provision of a lower setting is due to safety regulations of Underwriters Laboratories. The receiver would overheat if being tested into a 4 ohm load continuously(which your speakers don't do)at full rated power. The lower setting reduces the available voltage from the receiver power supply section so that full power isn't available and overheating is less likely. Tests have shown that this can roughly cut the maximum power capability in half and make clipping more likely. Bad move; don't even try it.
