What component is responsible for dynamics ?

OF course, being hard of hearing could be another explanation for the system not sounding as loud as it is. :^)

I've heard the effect Ralph describes on some amps but not others in recent years. Mostly with tube and Class D type amps.

Impact is a good term .
What I am refering to is the 'aspect' of a system that makes you want to tap your foot , bob your head , play air guitar , conduct the orchestra or get up and boogy !
I have another set of cheapy speakers that offer some of these characteristics . Now granted they don't have the extension , detail or clarity of my other speakers but they are exciting . If I could find something that combines these two speakers together that would be nice .

Great response Atmosphere. You've hit it right on the head.

Atmasphere, I don't think the human ear judges loudness in audio. Certainly we can sense loudness outside our listening room and there it isn't distortion. I would entirely agree that more efficient speakers tend to be more dynamic, however. I once had all compression drivers in horns except for the deep bass with flyweight 1.56 watt amps. The impact on you of a snare drum would just about knock you backwards.

I really think dynamics are about the leading edge but it about low impedance ac power. Also with my recent experiences with High Fidelity Cables with the "magnetic conduction" technology, I think metals have different effects on leading edge and dynamic. These cables are substantially more dynamic than any others I have heard.

I would agree that some speakers don't sound loud when they really are. Also I am consistently playing my system at a louder volume setting and sound pressure setting than with other cables. And my wife down stairs has not once complained.

Ralph, my experience is exactly as you describe but interestingly, much more so when the Acoustat amps I'm speaking of are in bridged mode. Far more dynamic(or distorted). In either case, very life-like. In stereo it is much more source dependent.