Most high-quality loudspeakers are 4-Ohms

16ohms or or so can sometimes be better sounding. And a easy load for most all amps. 4 ohms is easy to design for try keeping a 3 way or 4 way loudspeaker 16ohms not a easy design chore. But to be fair 4 ohm designs can sound great as do 8 ohm or 16 ohm. Just depends on total design and system said loudspeaker will be used in. In loudspeakers its the design and parts used that maters most the ohm loads more a issue when selecting amplifier.

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