I was trying to bi-amp Kappa 9, using 20W 6L6 Push-Pull tube amp to high and 300W SS amp to low. Out of curiosity, I just connected the 20W tube amp to both, and see how it sounds. WOW, very very surprise, it sounds much better than bi-amp. I even used the extended bass mode. Its the best sound Kappa 9 I ever heard. It even has one of the best bass compared to high current SS amp. And I listen loud classical music in a 21'X14' room. The 20W push the kappa 9 without a drop of sweat.