More resistance is less load??

Thanks this is very helpful. I agree falconquest it is counter-intuitive, but the equations and explanations are clear & helpful. I have some clarity now.

almarg has brought up the notion of "power".

Used to be, when I paid attention to these things, 40 watts per channel was 40 watts "RMS".

How is RMS (root mean square I believe) to be understood?

almarg - believe it or not I didn't "realize, the signal provided to a speaker consists of various frequency components each of which is AC (alternating current)".

I'm kind of amazed, now, at how little I know and how little I questioned. This stuff is actually quite fascinating.

Ok, here's another question: why can't the resistance from the speaker, that the amp relies on be built into the amp itself? Why build a product that has a vulnerability even though the manufacturer knows the amp will be paired with an unknown speaker, of unknown quality and impedance?

almarg - ok, here's a variation of the question. When building an amp, couldn't the manufacturer's assume the worst - that speaker resistance, while "typically" 4-8 ohms will occasionally get very close to zero and build the amp on that basis?

Almarg, thank you for your elegant, articulate and patient responses!