How are speakers improved?


Lets look at a hypothetical example of a speaker designer. Lets call him Nigel. Now Nigel has made a bookshelf speaker. It uses state of the art drivers and a braced MDF box. The crossover is 4th order linkwitz riley @3khz. All very typical so far. The speaker is almost ruler flat within its operating range. Off axis is even and quite flat. Distortion is within typical limits. 

He listens to it and sends it off to some reviewers. The response he gets is lukewarm. Its neither good or bad. 

The questions are:

1.) What does Nigel need to do to IMPROVE the speaker beyond its existing performance?
2.) What parameters need to be improved in order to elevate the performance to an even higher standard? 

WHAT IS THE SECRET TO PERFECT SOUND THAT HAS ELUDED NIGEL???
kenjit
Nigel needs to install furniture shakers so that he thinks he did something different than everyone else
1. Piano black and 2. quadruple the price.
That would certainly trick audiophiles into thinking there had been an improvement. But it wouldnt be real. 


I don't know who this Nigel character is, but I can say the furniture shakers are a huge hit with the ladies.
kenjit the answer is obvious Nigel needs you to come and tune his speakers for him.