What is your take on high efficient speakers vs. low efficient speakers?

@atmasphere wrote:

My Classic Audio Loudspeakers are 98dB and flat to 20Hz. They employ dual 15" woofers as well as field coils to reduce distortion and compression while increasing speed.

I guess one could even argue, given their 16-ohm load, that they're 101dB sensitive from the usual 8 ohm standard sensitivity is measured by. Not to mention that many speakers today are closer to a 4-ohm load, yet without being accurately reflected by their sensitivity rating.. 

^^ Yes. The difference between sensitivity and efficiency specs is poorly understood. You have to do math to convert from one to the other unless the speaker impedance is 8 Ohms.

What a thread...

Is a speaker with 88db sensitivity at 8 ohms or an 88db sensitivity at 4 ohms more "efficient"?

Having listened to gear for 20 years and owned a variety of equipment, I tend to associate higher sensitivity with a brighter sound. I lean to lower-sensitivity speakers in general.

@smoothtech 

If the loudspeaker has a different nominal impedance than the volts needed to achieve a watt also changes. Some manufacturers calibrate their one watt to the different impedances. Other manufacturers stick with 2.83 volts regardless of impedance. This is why we need to be careful about reading specifications.

If we have a 4 ohm cabinet then 2.83 volts is actually 2 watts. As we have doubled the power the loudspeaker sensitivity will appear 3dB louder.

Is this fair?

Imagine that you have two loudspeakers. Both loudspeakers have a sensitivity of 100dB referenced to 2.83v at 8 ohms at 1 meter. Your black loudspeaker is an 8 ohm box and your white loudspeaker is a 4 ohm box. You put them both on a separate channel off the same amplifier and play some music. You hear that your white speaker is twice as loud. Should both these speakers have the same sensitivity in the spec?
We would argue that referencing to 2.83v is more honest than specifying a nominal 1w/1m. It makes it clearer what your input signal is.

Quick Reference

Please use the table below as a quick reference to help you compare sensitivity measurements calibrated to different values.

Some members seem to advocate whether high efficiency speakers are better or not.  Sonics is my priority not speaker efficiency.  I only address speaker efficiency if it is required/driven by a sonic goal- wanting to hear flea watt 300b tube amp magic which would necessitate a very efficient speaker.