Speaker ratings, how to interpret?

Clueless, First, we need to distinguish between measurements and specs. Specs ARE marketing material, and I've yet to see a spec sheet that really told me anything I would trust.

Now, the right kinds of measurements can tell you plenty about the performance of a speaker, but those measurements are represented by 2- and even 3-dimensional graphs, not numbers. And very few manufacturers publish such graphs.

As for underpowered amps, leaving aside the extreme cases (5-watt SETs driving huge sealed boxes), the best test is to listen for clipping distortion.

Marakanetz: Actually, Boyk said it about ALL spec sheets. The only way to know if a particular amp has enough oomph to drive a particular speaker is to put both in your listening room, and crank up the volume (slowly!).

The nominal rating is the impedance the speaker manufacturer wants you to think the speaker is. The minimum impedance is closer to what really matters: what's the toughest load a speaker presents to an amplifier? (Impedance varies with frequency, as you may already know.) But when I see a minimum impedance of 4 ohms, I generally assume that means "3 ohms."

As for amps, it's not so easy. What you'd like to know (among other things) is how much power the amp can produce in a short burst at the frequency at which your speaker's impedance dips to its lowest point. But your power spec is for a continuous tone (by government fiat, by the way), usually at 8 ohms.

As James Boyk once wrote, the only two specs that mean anything are the dimensions and the weight. The dimensions tell you whether it will fit on your shelf, and the weight tells you if your shelf can hold it.

Yes, Clueless, I kinda suspected you and I were more in agreement than not. "Measurement" sometimes seems to be a dirty word around here. It needs people to stick up for it.