http://klipschupgrades.com/dansessay.shtml
http://klipschupgrades.com/whattheysaid.shtml
I can't comment on the K-horns but I did do the whole upgrade to my Belle's and they sound so much better in every way. Tighter and cleaner bass which seems like it goes lower than before. Much smoother highs, and the Mids are so much more open and fluid, more realistic and pleasing.