"I don't understand how a 4" driver, even if has high efficiency due to horn loading, can move enough air to have much dynamics."
Its all relative and depend on room size but basically teh answer is it can't compete in an apples/apples test.
Unsound, even if you consider them deficient, what are the best sounding horns you have heard?
The best I have heard are custom GoTo horns. I did not get to hear them over an extended period of time, but what I heard was quite good and with my eyes closed I do not think I could have guessed they were horns other than the fact that the dynamics were superlative.
