What component is responsible for dynamics ?

When it comes to electronics, I have yet to hear another company that manufactures amps and preamps to compete with CAT in the context of dynamics (contrasts). And so far, the Dream State Dream Catcher is the most dynamic power cord I have heard as well. As far as which specific link in the change will affect this the greatest, there never is such a link that is the most important or contributing in any category.

all of them (IMO) but,

a reasonable approach would be to get some high efficiency full range speakers and the proper power amp.

but the answers are going to be all over the place.

Hmm.. To simplify, perhaps grossly, and to generalize, I would say power amp and turntable itself, not arm or cartridge, or cd transport. Stable current from the wall is very important too, of course.

Everything in the system, from the quality of your AC, to the size/layout of your acoustic space, can and will affect the dynamics of what you hear.