An emergency message output amplifier (30a, b, c, d) includes a plurality of audio output channels (28a, b, c, d). Channels can be combined together to increase output power, and can be isolated from respective output speakers (26a, b, c, d) in response to detected faults and then disabled. The functional amplifier can be activated by itself and output current can be monitored to lower the output level enough to enable the amplifier to properly drive the existing load.
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