What component is responsible for dynamics ?

Sure : Reference 3A Di Capo i speakers
Primaluna Prologue II integrated amp
Granite 657 CDP

I am in a small 10ft. X 11ft. room with wall to wall carpet and 8ft. ceilings . I use some room treatments , 8th Nerve , consisting of pads in the corners and above the speakers where the walls meet the ceiling . I have the speakers and listening position set up on the diagonal with the listening position and speaker seperation set in an equal lateral triangle of 6ft . The speakers are firing staight forward , no toe in .
I play the CDP through the tube side using the stock tube.
The amp has had the tubes rolled to EH EL34's on the output and Mullard 12AX7 & Radiotechnique 12AU7 on the input . I am using a M. Wolffe Source P/C and ZSquared au/au IC's .

Hope it helps.

Individual components won't guarantee proper dynamics in a system. In order to preserve the dynamics in a recording it is essential to have a system with suitable gain structure between components. If you can't turn your volume control past the 9 o'clock position without your system getting too loud, then your gain structure is off. Similar mismatches can occur between the preamp/amp or amp/speaker. It's not as if there are perfect interfaces between components, but there are wrong ones and those will degrade your system's dynamic performance.

Regarding loudspeaker, I don't think that higher efficiency is what makes some speakers sound more dynamic, instead I think it's related to larger driver area and the amount of air that is excited. It's my observation that loudspeakers with twin 15" drivers have greater dynamic capabilities than a loudspeaker with a single 6" cone. The reasons why are obvious and if you wanted to reduce it to a simple statement -- small speakers won't sound as dynamic as larger speakers, assuming appropriate caveats.

Agree w/"Onhwy". For better dynamic capability in loudspeakers, driver Sd does matter. Such drivers tend to be of higher sensitivity and have (paradoxically)relatively shorter Xmax. At equal loudness they generally sound more open. For home audio many are be found in 2 way designs with a compression driver on top (just one example is http://lsv-achenbach.de/kits/tricolore.htm).

Saki70, The Prologue II is a nice amp but not known for its dynamics, IMO. Experimenting with tubes might get you closer to where you would like.

Without a doubt, the LP or CD recording engineer. I have not read all the responses but dynamics are determined by the source material one is listening to. That said, on the component side, speakers and amplifier determine the systems ability to reproduce great dynamics. Keep in mind that any system regardless of price can actually produce the full dynamics of the recording as long as the loudest passages are at volume levels under the maximum spl for the system as a whole.

In other words, if I am playing a Telarc CD with difference of 50 db between its lowest and loudest passage, and I set my volume level to produce about 100db on its loudest passage(which is not very loud), when the orchestra crescendo's between that soft to loud passage most systems will accurately render this. Compression of dynamics starts to occur when you near the physical limitation of the drivers.

Where a great system comes into play is producing substantially louder passages, say at 110db or even 120db, without compressing the music. This limitation is driven by the efficency of the speaker, the size of the speaker, and the amps power. That's why a small speaker, like a totem dreamcatcher, with a 4.5" woofer is limiting. Its maximum spl might only be 102db (100db without compression) which puts the floor of some orchestral passages below the ambient room db level (due to a/c units, heating ducts etc).

Unfortunately for most audiophiles, many modern recordings are now compressing music and placing all instruments and vocals at loud levels due to the prolific use of personal music systems like ipods and automobile listening. This is to compensate for high background noise levels from road noise or public spaces.