Rvr, you didn't say if you're actually using the 4 ohm setting, but despite the language in the manuals, such settings should never be used. They're simply a fire safety related feature required for UL(Underwriters Laboratory)approval. They operate by reducing the voltage which the power supply section of the unit can output, and following Ohm's Law, when the voltage is reduced so is the current and power. So, although it might help prevent overheating, tests have shown that the maximum power capacity is cut roughly in half.
