Everyone is sort of missing the real cause & effect..... It's not impossible to make drivers and speaker systems that are 97dB efficiency, but they will have far from flat frequency response or tight transient response. (though they can still sound musical). Very light drivers with large magnets, and/or horn loading will have peaks & valleys in their frequency response due to undamped resonances. In a magical world, you would raise those dips UP to meet the peaks, and have a high sensitivity speaker with a smooth response. But that's not reality. All we humans can do is damp those peaks down by adding mass, stiffness, damping, whatever, etc. By the time you are done tapping down all those nasty peaks, you are down to 90, 88, maybe 86 dB.... all depending on about a million variables and design choices. Then you put it out into the world, and see if people like what you did. Nobody sets out to make a low sensitivity speaker as a goal.
