Hi Aberyclark,
It is not cast in stone, but generally multiple drivers give you higher sensitivity. There are many designs that don't need multiple drivers to give that sensitivity. Sensitivity on its own does not improve the sound of a speaker at low volume, it just means that you don't need much power to drive it. On the other hand. I do believe that sensitivity almost always improves dynamics. This is in general, there are lowerer sensitive speakers that with the right power can be very dynamic. Its just most high sensitivity speakers are dynamic.
It is not cast in stone, but generally multiple drivers give you higher sensitivity. There are many designs that don't need multiple drivers to give that sensitivity. Sensitivity on its own does not improve the sound of a speaker at low volume, it just means that you don't need much power to drive it. On the other hand. I do believe that sensitivity almost always improves dynamics. This is in general, there are lowerer sensitive speakers that with the right power can be very dynamic. Its just most high sensitivity speakers are dynamic.