An amplifier of any kind is but a modulated power supply

Hi,
I have just read this sentence from the page: https://www.pgmusic.com/forums/ubbthreads.php?ubb=showthreaded&Number=167301
An amplifier of any kind is but a modulated power supply.
Could anyone kindly explain it?
Thanks.

hi,

An amplifier does not generate or create power.

The current output to the load connected to the amplifier is supplied by the power supply, so it is correct to say the amplifier modulates the current drawn from the power supply flowing in the amplifier load.

E

It's often been mentioned here over the years.

However, the link given is pretty wrong in most counts - for example claiming that FET's lowered weight and cost of amplifiers - if anything they might have made them heavier, as slightly larger mains transformers are required to give the same amount of power.

Thanks Eric and Nigel,
I have misunderstood about amplifier for a long time! Now I can see the importance of power supply.