Raul, I do agree that there are some favorable characteristics to both SS and tube designs.
However, it appears that you are attempting to engage in some kind of "specs race" between SS and tube amps. Distortion Specs are only useful in some regards, and are not indicators of performance in a music system. The methods used to measure them are not the same as the intended use of musical playing, and therefore may have little or no bearing on the actual musical performance of the amplifier. Static sine-wave distortion measurements into a dummy load are not even close to the way an amp produces music. Most informed users do not rely on these specifications. The ear can hear distortions produced by a design that do not show up in any measurement protocol.
Regarding "complementary transistors", they are only applicable in Class AB or B amplifiers(push-pull), which require switching, phase-splitting, or both, and are not the equal of true Class A design(no phase-splitting or switching) for musical reproduction. But I agree that complementary Class AB is nice to use when you need a high power amp that cannot run totally in Class A all the time, for use with certain difficult speakers. But it is obvious that virtually all Class AB SS amp makers bias them as high as possible, to keep the amp in Class A as much as possible. This is simply a "de facto" example that any kind of Class B(complementary or not) cannot compete with Class A sonics of a similar quality level amplifier(maybe even from the same manufacturer). They just do this switching to Class B so they can output more power without as much wasted heat. Not for better sonic performance than Class A.
Regarding your comments on "unwanted harmonic content", which I suppose means "harmonic distortion", you only have to look at harmonic distortion curves of various amplifier designs to see that SS amplifiers have relatively low amplitude harmonic distortion characteristics, but have them all the way up the spectrum, and have them primarily in odd-order content, which makes them much more objectionable to the ear, and therefore they have to be lower to be even listenable. Tube amps, on the other hand, especially Single-Ended Triode amps, have a somewhat higher amplitude harmonic distortion curve, but it is located primarily(almost completely with SET) at the 2nd harmonic interval, and is almost all even-order distortion which is easier on the ear, and also easier to deal with by other aspects of design. Push-pull tube amps are not as good in this regard as SET, and suffer from both odd and even order harmonic distortion, as well as the phase-splitting and complementary amplification things. But they can be good sounding amps nonetheless, if they are designed and built well(typically with some negative feedback that was well applied).
Regarding your discussion about output transformers, this is the crux of your previous discussion that included output impedance of tube amps and their performance with reactive speakers. The tubes have higher output impedances than transistors, and usually must have impedance-matching output transformers to achieve a low enough output impedance to drive a speaker load. This is well-known. I agree that there are problems associated with output transformers. However, very good output transformers achieve a very high level of performance, and mitigate the problems to a large degree. OTL and ZOTL can eliminate these output transformers, but traditional OTL must resort to parallel-ganging of the output tubes to reduce the output impedance to a useful level(which is still usually a bit too high, but works), and only ZOTL allows the use of true SET Class A single-tube output, with impedance matching to the speaker that is under 2 ohms,no output transformers, and devoid of the typical transformer artifacts. As you know, this is a unique circuit from David Berning, and it the circuit used in my personal amplifier. The distortion from this(my personal) amplifier has total harmonic distortion of much less than 2% in the audio spectrum and the predominating location is at the 2nd harmonic(with much much less in the rest of the spectrum). Output impedance with 0 feedback is under 1.8 ohms. The circuit is true Class A(no phase split) and has a single output triode per channel, which negates any need for any "complementary devices". Bandwidth extends to 500khz. It can produce a square-wave anywhere in the audio range. True full-power bandwith is produced down to 2Hz(where a coupling cap intercedes to avoid DC), and this produces very prodigious and fast bass response. Signal-to-noise ratio is better than -100db(quieter than most SS amps). Supersonic(RF)frequencies are used to heat the tubes, for heater noise elimination and long tube life. The amp is 12vdc powered to eliminate line noise. It has choke-loading for improved linearity. Super short signal path. Ultrahigh-speed switching power supply that is very stiff. Overall, this amp is about the most advanced and most musical amplifier that I have ever heard or seen, and it is a tube amp. I realize that specs are not the answer, as I mentioned earlier, but if you want some specs, there they are.
If you want to quibble about the 2% total harmonic distortion spec on my amp, then it would be useful to note that the single-driver speakers that I use have a similar 2% harmonic distortion profile at the 2nd harmonic primarily, and the judicious connection of the speakers at 180 degree phase angle to the amp outputs cancels much of the overall system harmonic distortion, and results in an overall system distortion much lower than any competing SS or tube amp with multi-driver speakers( which have wide ranging additive distortion profiles and cannot benefit from this happy matching). See the articles by amp designer Eduard de Lima on SET amps and single-driver loudspeakers, available with a web search.
I have no "axe to grind" against SS amps in general, and there can be some very nice SS amps. I have owned and heard many. My main purpose for my posting here, is to rebut the premise that you have made, which states that tube amps cannot be serious musical amplifiers. I hope I have done that. Nothing is perfect. Bliss is in the ears of the beholder.
However, it appears that you are attempting to engage in some kind of "specs race" between SS and tube amps. Distortion Specs are only useful in some regards, and are not indicators of performance in a music system. The methods used to measure them are not the same as the intended use of musical playing, and therefore may have little or no bearing on the actual musical performance of the amplifier. Static sine-wave distortion measurements into a dummy load are not even close to the way an amp produces music. Most informed users do not rely on these specifications. The ear can hear distortions produced by a design that do not show up in any measurement protocol.
Regarding "complementary transistors", they are only applicable in Class AB or B amplifiers(push-pull), which require switching, phase-splitting, or both, and are not the equal of true Class A design(no phase-splitting or switching) for musical reproduction. But I agree that complementary Class AB is nice to use when you need a high power amp that cannot run totally in Class A all the time, for use with certain difficult speakers. But it is obvious that virtually all Class AB SS amp makers bias them as high as possible, to keep the amp in Class A as much as possible. This is simply a "de facto" example that any kind of Class B(complementary or not) cannot compete with Class A sonics of a similar quality level amplifier(maybe even from the same manufacturer). They just do this switching to Class B so they can output more power without as much wasted heat. Not for better sonic performance than Class A.
Regarding your comments on "unwanted harmonic content", which I suppose means "harmonic distortion", you only have to look at harmonic distortion curves of various amplifier designs to see that SS amplifiers have relatively low amplitude harmonic distortion characteristics, but have them all the way up the spectrum, and have them primarily in odd-order content, which makes them much more objectionable to the ear, and therefore they have to be lower to be even listenable. Tube amps, on the other hand, especially Single-Ended Triode amps, have a somewhat higher amplitude harmonic distortion curve, but it is located primarily(almost completely with SET) at the 2nd harmonic interval, and is almost all even-order distortion which is easier on the ear, and also easier to deal with by other aspects of design. Push-pull tube amps are not as good in this regard as SET, and suffer from both odd and even order harmonic distortion, as well as the phase-splitting and complementary amplification things. But they can be good sounding amps nonetheless, if they are designed and built well(typically with some negative feedback that was well applied).
Regarding your discussion about output transformers, this is the crux of your previous discussion that included output impedance of tube amps and their performance with reactive speakers. The tubes have higher output impedances than transistors, and usually must have impedance-matching output transformers to achieve a low enough output impedance to drive a speaker load. This is well-known. I agree that there are problems associated with output transformers. However, very good output transformers achieve a very high level of performance, and mitigate the problems to a large degree. OTL and ZOTL can eliminate these output transformers, but traditional OTL must resort to parallel-ganging of the output tubes to reduce the output impedance to a useful level(which is still usually a bit too high, but works), and only ZOTL allows the use of true SET Class A single-tube output, with impedance matching to the speaker that is under 2 ohms,no output transformers, and devoid of the typical transformer artifacts. As you know, this is a unique circuit from David Berning, and it the circuit used in my personal amplifier. The distortion from this(my personal) amplifier has total harmonic distortion of much less than 2% in the audio spectrum and the predominating location is at the 2nd harmonic(with much much less in the rest of the spectrum). Output impedance with 0 feedback is under 1.8 ohms. The circuit is true Class A(no phase split) and has a single output triode per channel, which negates any need for any "complementary devices". Bandwidth extends to 500khz. It can produce a square-wave anywhere in the audio range. True full-power bandwith is produced down to 2Hz(where a coupling cap intercedes to avoid DC), and this produces very prodigious and fast bass response. Signal-to-noise ratio is better than -100db(quieter than most SS amps). Supersonic(RF)frequencies are used to heat the tubes, for heater noise elimination and long tube life. The amp is 12vdc powered to eliminate line noise. It has choke-loading for improved linearity. Super short signal path. Ultrahigh-speed switching power supply that is very stiff. Overall, this amp is about the most advanced and most musical amplifier that I have ever heard or seen, and it is a tube amp. I realize that specs are not the answer, as I mentioned earlier, but if you want some specs, there they are.
If you want to quibble about the 2% total harmonic distortion spec on my amp, then it would be useful to note that the single-driver speakers that I use have a similar 2% harmonic distortion profile at the 2nd harmonic primarily, and the judicious connection of the speakers at 180 degree phase angle to the amp outputs cancels much of the overall system harmonic distortion, and results in an overall system distortion much lower than any competing SS or tube amp with multi-driver speakers( which have wide ranging additive distortion profiles and cannot benefit from this happy matching). See the articles by amp designer Eduard de Lima on SET amps and single-driver loudspeakers, available with a web search.
I have no "axe to grind" against SS amps in general, and there can be some very nice SS amps. I have owned and heard many. My main purpose for my posting here, is to rebut the premise that you have made, which states that tube amps cannot be serious musical amplifiers. I hope I have done that. Nothing is perfect. Bliss is in the ears of the beholder.
