An audio amplifier system includes two amplifiers that are configured to drive
loads through either DC or AC coupling. A third amplifier provides an AC ground
return when the system is configured in the DC coupled mode, and is disabled when
the system is configured in the AC coupled mode. A bypass circuit charges a bypass
capacitor to provide a reference voltage level for the amplifiers. A mode detection
circuit monitors the reference voltage level and the output of the third amplifier
to determine the current operating mode. The third amplifier is disabled when the
reference voltage exceeds the output of the third amplifier or when a shutdown
condition is activated, such that the third amplifier is protected from short circuit
conditions. The charge and discharge times of the bypass capacitor relate to the
detected operating mode minimize click and pop in the amplified signals.