Bifwynne, another speaker you might look at is Audiokinesis. His speakers are not only more efficient, they are also very easy loads (some of them are 16 ohms) without crazy phase angles, yet also quite musical and good bass extension.
I think you are correct that speaker manufacturers ought to be taken to task. Back in the old days when tubes were the only game in town, speakers were a lot more efficient and higher impedance. When the less expensive power of solid state came along, we saw both impedance and efficiency go down.
When transistors came along, amp manufactures realized they could build an amp with same power as a tube amp, but it might only cost 1/10th as much, yet they could still charge 90% of the tube amp retail cost. A similar thing was going on with speakers- its costs about 1/10th as much to build a lower efficiency driver (as opposed to a high efficiency driver). To get back some of the perceived loss of efficiency, the impedances headed south. IOW, its all about the dollars.
IMO its telling that you can have two speakers, one 10X more efficient, and the more efficient one can have the same bandwidth and be just as revealing, IOW not giving up anything for being more efficient.
I can't think of a good reason for a high end audio loudspeaker to be less than 8 ohms. I've mentioned this plenty of times before- the lower the impedance, the higher the distortion, making any amplifier harsher and less detailed due to the types of distortion and our human hearing/perceptual rules. IOW if you want to make a speaker that seems smoother and more revealing, all you have to do is increase its impedance (all other things being equal- same box characteristics, same crossover points). It will not be that the speaker itself is all that different, but the sound of the amp driving it will be!
