What component is responsible for dynamics ?

What component is responsible for dynamics ?
If one is looking to increase the dynamics of their system , what one component will offer the most beneficial change ?
Saki70

Saki70, you will find your answer once you answer this question (in return): which part of your body is responsible for your good health? I.E. if you were looking to improve upon your health, which organ or part of your body would you concentrate on to get yourself in (even) better health?

This same characteristic applies to speakers. Hence the more effecient your speaker are, the louder you can drive the max spl without compression.

you have ASSUMED too much in your statement that the amp driving the inefficient speaker does not have the current drive capability & dynamic headroom to drive that particular inefficient speaker. That is NOT always the case - there are plenty of well-made amps that have sufficient prowess to drive inefficient speakers. They might not fit your budget (or that of most people) but that's another matter.

This is also the reason that speakers with large and many drivers can give you great dynamics in a good size room.

Again, you've assumed too much by giving a lot of speaker manuf undue credit by assuming that they know how to design a multi-driver speaker. Most do not! The audio landscape & used market is full of multi-driver loudspeakers that sound blah...
There are some multidriver loudspeakers that fit your statement but it usually the exception.....