>>> Huh?  You are saying that they deliberately make speakers less 
>>> efficient so that a higher voltage can be used to drive them?  I've 
>>> never heard that before.
>>
>> Yes.
> 
> Interesting, how do they do that?

You think *I* know?

> Hard to see how you could deliberately make the system less 
> efficient without just plonking a huge 50W resistor in series (which 
> would totally screw up the quality of the sound).

And why would that be?

>> Hmm, I think my amplifier (nothing special) is rated at 60 W per 
>> channel. (IIRC, into 8 ohms at 1 kHz.)
> 
> And what happens when you actually output 60 W in your room?

Well obviously I'm unlikely ever to try this. (It's like all toasters 
have a special setting that transforms bread into charcole. We don't 
know why, but they all have it.)

By the way... I notice with interest that the sound level drops 
*dramatically* as you walk through the doorway. I mean, it's really 
drastically quieter just slightly outside the door. I am be half-deaf 
inside my room, and yet from outside it doesn't seem all that loud. 
Really. You'd think the sound would travel more.

(Perhaps this is related to the mysterious "waves can't pass through 
holes smaller than a certain size" phenominon?)

> BTW on 
> most amplifiers you need to get the input signal at the right level (not 
> too high or too low) to get the quoted maximum output power.

Yeah, probably.

(I once tried connecting a line-level output to the phono input. Big 
mistake...)

> I guess 
> also your ears work on a logarithmic scale, so 60 W is probably not as 
> much "louder" than 20 W as you would think just by looking at the numbers.

Yeah, most human senses actually seem to work in a logarithmic way... I 
suppose that means they work well under "all conditions" or something.

>> Wait... the *voltage* changes depending on how much you use it? That's 
>> odd. I thought that potential difference was always constant, and it's 
>> only *current* that changes...
> 
> That's only true if all the cables in the whole system have precisely 
> zero resistance, which they don't.

Really? How interesting...

-- 
http://blog.orphi.me.uk/

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