Kudos to Dr. Geddes but he has apparently rediscovered what has been the accepted wisdom in audio for probably more than 20 years. The only way to account for the fact that many folks prefer tube preamps and amplifiers despite the fact that they typically have higher measured distortion than SS devises is to posit Dr. Geddes conclusions, and many others have studied this phenomenon and no doubt also presented findings to the AES and like groups. IMO, one of the reasons why SET amplifiers have such a devoted following is that these devices tend to have a very low distortion at low power levels which increases pretty linearly with increasing power demands. PP amps, on the other hand, tend to have higher distortion at the lowest power levels, near the cross-over point, than they do further up the scale.
As far as Atma-sphere amplifiers damaging a speaker, I think it's highly unlikely to occur even if every single output tube were to go sour simultaneously. What is being said, Raul, is that the amp won't damage a speaker, not merely that it will not damage itself. I have a pair of Atmas with an aging output tube set. Consequently, once in a while one of the fuses on the output tubes will blow due to the tube arcing over (each tube is separately fused). This results in a barely perceptible decrease in power and decrease in the wonderfulness of the sound, but not even a hint of anything that could possibly damage a speaker, i.e., no pops, bleeps, ticks, screeches, etc. Nada. So, while I don't mean to infer that you, Raul, are being untruthful, I do think that whatever happened during that listening session to damage the speaker did not occur directly as a result of the amplifier malfunctioning. Something else was going on.
As far as Atma-sphere amplifiers damaging a speaker, I think it's highly unlikely to occur even if every single output tube were to go sour simultaneously. What is being said, Raul, is that the amp won't damage a speaker, not merely that it will not damage itself. I have a pair of Atmas with an aging output tube set. Consequently, once in a while one of the fuses on the output tubes will blow due to the tube arcing over (each tube is separately fused). This results in a barely perceptible decrease in power and decrease in the wonderfulness of the sound, but not even a hint of anything that could possibly damage a speaker, i.e., no pops, bleeps, ticks, screeches, etc. Nada. So, while I don't mean to infer that you, Raul, are being untruthful, I do think that whatever happened during that listening session to damage the speaker did not occur directly as a result of the amplifier malfunctioning. Something else was going on.