Palmer PGA04 Manuel D'utilisation page 10

other openings. Do not be alarmed: your device does not contain any
components that are about to "burn down". However, as already mentioned
above, you should always make sure that sufficient airflow is provided
for adequate heat dissipation. It should be pointed out that power tubes
do wear out, depending on the delivered output power of the amplifier.
Therefore, if you continuously operate your amp at high levels, you can
expect an increased wear of the output tubes.
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