The minimum amount of power needed to move the speaker diaphragms enough to make sound and the maximum safe power before over-excursion of the drivers occurs.

 

Loudspeakers require sufficiently large input power to reproduce sound, but an under-powered loudspeaker may produce hard clipping (distortion) which ultimately causes the voice coil windings to overheat, resulting in a dead speaker.  Too much power and the voice coil over-extends, resulting in a blown speaker. More speakers are damaged from under-powering than from over-powering simply because the damage is cumulative and not heard as distortion until it’s typically too late.

 

Rule of Thumb:

In the real-world, it’s best to ignore the low-end spec. That’s shown to show the minimum amount of power needed to move the voice coils in any appreciable manner.

 

A good match is an amplifier capable of producing between 60% and 110% of the recommended maximum. 

 

For example, the R5 shows a Recommended Amplifier Power of 15 to 200 WPC. A good match for this speaker would be an amplifier that produces between 120 Watts per Channel ((200x.6)*100) and 220 WPC ((200x1.1)*100). In terms of performance and damage potential, an amp rated lower than 60% of maximum poses far more danger to the loudspeaker than an amp rated above the maximum.