In the two test samples, it appears the tube amp adds predominantly second or even order harmonic and the solid state amp adds odd order harmonic (at a comparatively lower level (amplitude?)). It may be worth noting that the authors complained of significant hum in the tube amps tested, which could affect the output, but I'm ready to accept that both tube and solid state amps add harmonics to the source material.
The tests were performed on a 50khz pure sine wave. I am interested in seeing the results of similar test feeding the complex waves of a real instrument, say the strike of an "a" on the piano. Is that test data available comparing a tube amp to a solid state amp?
The tests were performed on a 50khz pure sine wave. I am interested in seeing the results of similar test feeding the complex waves of a real instrument, say the strike of an "a" on the piano. Is that test data available comparing a tube amp to a solid state amp?

