I have a 20 W amplifier. If I plug a box with a 100 W speaker, does the sound get "louder"?
We always explain that energy can not be created. If the amplifier provides 20 W of power (energy per unit of time) whatever you turn on at the output of it can not provide more than 20 W of sound. So even if the speaker used is 100 W, when you put your amplifier at maximum still you will have 20 W of sound. What needs to be observed in this case for good performance is that the speaker has a power that is equal to or slightly higher than that of the amplifier, so that it is not forced, and that the impedance of this speaker is that required to obtain the desired power. For example, an amplifier that provides 20 W with 4 ohm, will provide less with 8 ohm.