Most high-quality loudspeakers are 4-Ohms

JohnK of course your point begs the question; does a speaker designer have to make compromises in order to make speakers work with higher impedances?

I think in a lot of cases they could design a lot of those 4Ω speakers to have only an 8Ω load.That may take a lot more engineering,plus better parts in crossovers,drivers,etc.The result,higher cost.When you look through buyers guides,you will find a lot of pricey high end speakers that are 8Ω.With some manufacturers their top flagship will be 8Ω speakers,and
their cheaper models are 4Ω.And also the opposite.I have good and bad that are both.Sometimes a new version will come out with higher impedance.HT 2009 buyers guide examples.(Snell Illusion,$50,000,8Ω)( Snell C7,$9,000,4Ω)(Totem Arro$1,350,4Ω)( Totem Forrest,$3,495,8Ω)They vary all different ways.It's hard to say that 4Ω speakers are the best.Have you compared them to all the over $50,000 8Ω speakers to see if they really are better?♫

Putting on my speaker designer hat for a moment, if I have the option of allowing the impedance to drop to 4 ohms (or below) I can often get a bit more bass extension out of a speaker, and/or use more aggressive equalization.

On the other hand as long as they're not pushed into clipping, I think most amps sound better with an "easy" load (even if the amp is capable of driving a very difficult one). Neither the "nominal impedance" nor the "minimum impedance" tells the whole story, but rather the impedance curve plus the efficiency need to be examined in the context of the application.

My personal preference is to err in favor of amplifier compatibility, as some of the best-sounding amps are fairly load-sensitive.

Duke
dealer/manufacturer

Thanks Duke, that's what I expected.

I agree with Swampwalker - most really high efficiency speakers are 8 ohms or even 16 ohms. There are a great many of us who prefer these mostly vintage speaker types (that were designed for tubes, not solid state) to most if not all of the modern designs.