I recently repaired my old KG4s, but had to settle for K3Ks rather than K8Ks (found a set in good condition on ebay). I know the K3K was recommended by Klipsch as a replacement after production of the K8K ceased, but I cannot find Thiel/Small (or any other) specs for either. While I obviously couldn't A/B this, my sense is that the efficiency is somewhat lower, and I believe the bass extension of the system may be somewhat compromised. Does anyone know the difference between these two drivers?