Overall impression: The Khorns sound distinctly "sweeter" and fuller. There is greater, more precise separation of group-singing voices and of the inner voices of a symphony orchestra, particularly woodwinds. Plus, I encountered a major, pleasant surprise in the bass. The speakers sound fuller in the woofer range. I did not expect that, rather, I expected improvement basically in the midrange only. Al K. did say I would hear some improvement in the upper bass. It's counterintuitive and I don't what is the exact cause, but perhaps it is because of Al's default setting holding the midrange back 6 db (the level is adjustable).
Anyway, the Klipschorn woofers seem now seem literally to have "bloomed" and to be much more in the action than they were before. In fact, need for a subwoofer is now eclipsed. I am running the Khorns now as much without as with my Velodyne S1500R sub. The sub still comes in handy to "excavate" some deep-low to augment program material that is otherwise bass-shy.
Some specific listening examples:
The Beach Boys - Endless Summer: One hears each of the voices such as really to sense the presence and the different voices of the individual performers.
Other vocal music (Dean Martin, Dolly Parton): fuller sound and greater realism, they're truly in the room with you.
Piano music: greater fullness, realism and tactile presence.
Symphonic music. This is my forte, my primary listening. I am especially closely familiar with the sound of a local professional symphony on whose Board of Directors I sit, the Mid-Atlantic Symphony Orchestra (www.midatlanticsymphony.org). Since 2006 I have been making DVD's of selected MSO performances for archival and promotional purposes, using a Sony DCR-SR100 camcorder. .These are non-professional recordings using the camera's own microphone, which captures a commendably clear and articulate sound. Compared with the pre-ALK Klipschorns, the same recordings of the MSO sound sweeter with more precise instrument definition and separation, and fuller in the bass. Before, I had to crank the subwoofer to pull out bass to round out the sound. Now, the sub is essentially superfluous.
Other symphonic:
Boston Pops - Leroy Anderson's "A Christmas Festival." There is a passage where oboe and clarinet are playing in unison. The ALK upgrade separates the instruments so you can hear each. I had never before perceived that particular stretch as involving the two different instruments. Now I hear that clearly. Later in the piece where some really deep symphonic percussive bass comes in, the Khorns now pump that out way down low. They didn't before.
Acid tests: the famous Telarc Tchaikovsky "1812" with the Cincinnati Symphony and the cannon shots, and the Telarc Saint-Saens Organ Symphony #3 with the Philadelphia Orchestra. With either, no subwoofer necessary! 1812 - The strings shine, they are luminescent. One has a sense of hearing actual multiple violins rather than a generic string sound. The non-cannon-shots orchestral deep bass thumps and crescendi are tactile. The cannon shots themselves come through the Khorns as excitedly as you can imagine. In fact, I have never heard this recording as thrillingly reproduced as it is now on the new setup, since sometime in the 1980's when I heard it through 1500 watts into a set of then-$40,000 Stonehenge-like Infinity Reference Standard speakers at a now-defunct retailer called Excalibur in Alexandria, VA.
The Organ Symphony - Same general impression about the strings and about overall smoothness and precision as above. Plus, the opening and closing fortissimo portions of the Third Movement, played at volume, literally took my breath away. This was real, wall-shaking, pants-flapping sound, no kidding, like I had never heard before through those Klipschorns. Yet all undistorted and pure.
My "Mighty Klipschorns" are now just that. They now whisper and roar palpably more clearly, precisely and satisfyingly than before.