I agree with Atmasphere's response. people that consider purchasing active crossovers should first consult the speaker manufacturer to find out if any wave shaping is necessary in the crossover circuitry. This is not intuitive and you must speak with the speaker manufacturer to find this out. Several manufacturers, if not the majority incorporate wave shaping circuitry in their speaker crossover designs to compensate for cabinet issues, driver response issues, etc. Also, as has been mentioned, Khorns are extremely efficient and dont' require stupidly powerful amps to drive them. The issue of solid state vs tube is left up to you after extensive auditioning.
Tube Monoblocks for heavy music on Khorns
What tube monoblocks would drive Khorns the best for big bass/heavy metal music? I obviously can't go the SET route for the BEST sound. I was thinking about some BIG monoblocks to help the Khorns 15" driver REALLY move. My room is small. I could even experiment with adding a large sub like a Velodyne HGS18 in the future, too. However, price is an issue. Another interesting Idea, what horn speakers can really compete with Khorn for around the same money for reproduction of bass, Etc??