Well, "they simply recharged twice when the amplifier was turned off, " (your text from earlier post) - how an the rectifier diodes "recharge the capacitors" when amplifier is turned off as you write i.e. mains power is cut off?
It is you who has some explaining to do, not me.
"what else..." - hook up a digital scope, trace the dynamics of output terminal and power rails and you will probably find the cause.
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