Well, regarding "slowness": The K-horn, due to its size and design, sends out more bass energy into the room than a La Scala does (at the same amp output power) In fact, with a K-horn the room walls act as direct extensions of the woofer. If the room walls, floor, ceiling are not "solid enough", or if the room has a lot resonating material, there can be an "undesirable slowness"in the sound (less damping, late subsiding). On the other hand, pure bass, as it comes out the speakers, should be slow. This we could call the "desirable component" of the slowness. ( rumbling). A "high fidelity" reproduction of a bass sound should always be "slow".. Like the rumbling sound earthquake.. What I am saying, is, the better the bass reproduction of a speaker, the important is to have a "solid" room and furniture choice, in order to eliminate "unwanted slowness".