Not really answering the question that you posed (as I don't know if output can be reduced by a command) but the audio amplifier should not be receiving radio frequencies at 2.4 GHz!
Assuming that some part of the amplifier is being swamped by RF then you could first enclose the amplifier pcb or wiring in a metal screening can. It could be pick-up on the input wires to the amplifier (which should be screened cable anyway) - this can be reduced by passing the cable through ferrite beads and/or adding small filter capacitors at the input.
Basically the ESP is doing what it is supposed to do - the amplifier is not.
First of all thank you for your great job in basic for the esp! is really great!
about tx power, in the AT commands i use a command to set the db power: AT+RFPOWER
and i was trying to find it in this implementation,
in fact, the question is: is this implementation using the max rf power? (I wish)
Thank you again a best regards !