The numbers don't tell you if one component sounds better than another component, or if one component is more reliable or more functional or produces less heat.
I can agree to that, but I am sure you know what distortions mean. So at least one wise person (I assume) who knows about amps had said the following, in his conclusion of an article on distortions (IMD in this case):
Intermodulation Distortion (sound-au.com)
"IMD is far more difficult to measure and quantify accurately than 'simple' THD, but you can generally rest assured that if the THD level is sufficiently low, IMD is unlikely to be a serious issue. Despite all the claims that harmonic distortion measurements are 'pointless', they are nothing of the sort. Low THD means high linearity through the circuit, and if a circuit is sufficiently linear it's unlikely to generate serious IMD. There are factors that can change this, as linearity can deteriorate at higher frequencies (which may not be measured for THD). In general, if you get a good THD figure at 1kHz and low IMD with an SMPTE and/or ITU-R test, then it's time to listen critically to ensure that the measurements and what you hear are in agreement. Few amplifiers will disappoint if they provide good test results".
The difference between -120 dB, or 0.0001%, and -100 dB, or 0.001% is that -120 dB THD+N means even if your room's noise floor is 0 dB, that is inaudible, you can then say with confidence that THD+N at the -120 dB is absolutely inaudible because no one would listen to music at 120 dB peak or higher.
If THD+N is -80 dB/0.01%, someone (I would guess
@Matthew J Poes and
@RichB might
) can argue that their room is quiet, with near 0 dB noise floor, so they could hear the effects of distortions because music don't always mask, or at least not completely mask distortions even if such distortions fall into/below the noise floor, especially if the contents are predominately odd and of the higher order types. I am not one who believe that, as I stated multiple times, but again, there are people who don't want to rely on other conditions so they want the lowest possible distortions numbers in order to feel good about it.
Again, back in the days when 5 different magazines show the same NUMBERS, we don't just focus on the numbers because we listen to the components and speakers and overall system, not the numbers.
I get your point, but I don't think people like me or Golfx who want the best possible numbers on products within their bugets would focus on the numbers only. For me anyway, as long as the numbers clear what I consider the point of diminishing return, features, user interface, perceived reliability track record, the look, even customer support track record, will all need to be considered.
Case in point is when audiophiles buy a $5500 AVR just because of the numbers on ASR or on any other sites.
I am not sure if we have such a case to discuss at the moment, but you are referring to Golfx, I would wait and see his response, as he may..
Maybe this happened "back in the days", but I can't recall a time when people said they bought a $5500 AVR, instead of a Pre-pro, purely based on some noise and THD numbers.
Again, I am not sure if some one has actually said that, but you may be right, or may be not. Case in point,
@DJ7675 got his X8500H brand new for less than $3,000 iirc. The AV7706 is currently going for $2,499 so if I am in the market for one right now I would pay a little more for the AVR.
In this example, it is not just the big difference in the SINAD numbers. We all have different focus, priority and think differently, it is no wonder why so many people prefer prepro+amp while many others prefer AVR+ex amps or AVR+ex amp+int amps.