I know a similar question title has been asked, but I believe that does not answer my question (and I couldn't think of a better way to phrase the question).
I'm a bit confused by how exactly an amp can overload a speaker, and vice versa.
Many guitar amplifier speakers are 8Ω impedance.
If I understand correctly, the output amplifier (should) outputs a fixed voltage signal output regardless of what load is placed on it. If this step is wrong, please correct me.
So if there is a fixed voltage signal, (say, +-15V, i.e. 30V of swing) and if the speakers' impedance is ~8Ω (I understand it will vary with frequency but say it is around this figure), then how is the wattage varying with different amp combos even though the impedance is roughly the same? Is it that the voltage increases with higher wattage amplifier/speaker combinations.
For example a 10W combo with an 8Ω speaker vs a 100W amplifier connected to a 4 speaker cabinet wired for 8Ω impedance (parallel connect 2 series pairs of 8Ω speakers), the 100W is obviously louder. Is it that the output voltages of the 100W amplifier is more? Else how can you get the wattage to increase if you are keeping voltage and impedance constant?
What would happen if you connected the 10W amplifier directly to a 4 speaker cabinet? Would it overload the amplifier? Or just play it quieter? Theoretically, if the voltage is the same and the impedance is still 8ohms, the wattage should be the same, i.e. 10W through the 100W rated speakers.
If so, is this true then: when we say 10W 8ohm speaker, we mean its able to handle maximum peak voltages of (P=V^2/R, V=sqrt(PR)) ~9V. Whereas for a 100W 8ohm speaker, it is able to handle peak voltages of ~28V?
In what situation can you harm a speaker? By connecting a too powerful an amplifier to it? But then isn't that something that is recommended by many people? (Amplifier output of atleast 2x the speaker rating). If so then the voltage output of an amplifier is not fixed? It varies according to which speaker is connected to it? (even though the impedance is the same?)
In what situation can you harm an amplifier? By connecting too high a wattage speaker to it? Then why do I see so many people posting videos on youtube of 1/2W guitar amplifier builds connected to big wattage rating 4 speaker stack speakers or atleast even 2 speaker combinations?