Basic question about sensitivity

4. Specific Amplifier Requirements: Harbeth speakers have a nominal impedance of 6 ohms, which can be a challenge for some mainstream amplifiers. These amplifiers may not deliver enough current to drive the speakers to their full potential, potentially resulting in a less dynamic and detailed sound. This requirement for specific amplification options limits their accessibility to a broader audience, but it also attracts audiophiles who enjoy the challenge of pairing their speakers with compatible equipment to achieve the best possible sound.

 

Thanks, @ghdprentice , I am running a Cary V12 which is switchable between 50 wpc triode and 100 wpc ultralinear. I am currently running it in triode, and honestly, I do not think I would want to pair it with anything that I could not drive in its triode setting.

and a cabinet that contributes to….. output…not present in the…. input

@tomic601 , can you expound upon that?

OP,

I have Audio Research 160 amps. They operate either 140 wpc ultra linear or 70 wpc triode. Although the sound output is hardly different between the two… the triode mode is more musical to me. I have paired this amp with 90db sensitive Sonus Faber Amati Traditional speakers. Works great at any volume. 
 

Your Cary amp sounds great. If I were you I would want to hear the combination before committing, 

A cabinet that contributes to output is one that moves or is not inert. This can be seen in the waterfall chart. The cabinet is storing and releasing energy after the driver has reproduced the input. Some people like that.  

in the general context of my comments, i wouldn’t overly focus on a single specification or measurement. @ghdprentice had it right by advocating for hearing a particular speaker of interest w your amplifier.

The EPDR measurement used by Hi Fi News and Stereophile gives a better indication of how difficult a load a speaker will present to the amplifiers.

The B&W 800 series are a good example of speakers that are relatively efficient but difficult to drive.

I am currently driving a 4 ohm, 96 dB speaker with a 2 wpc SET.