Jerome, I am not surprised at your findings. The speakers have to be designed with low tube wattage use from the get go or the results will be unpredictable. No wonder some recordings may have sounded good while others did not. It's not even the efficiency as much as it is the tube friendly impedance curve that doesn't load the amp down that matters the most. 4 ohm nominal impedance does not work very well with most lower powered tubes, especially single ended triodes. That usually means that there is a dip even lower than 4 ohms somewhere and exactly how low, is hard to say but tubes are not very good current sources like solid state amps are. The 4 ohm speakers make it easier for the solid state amps which produce more power into lower impedance. The 2301's may be ok since they are push-pull and are 300w after all, not 30w.
I am surprised that Mr. Verdier didn't mention that to you. Sure his SET amps worked on your speakers in terms of making sound but was it an optimal situation?
