"Indeed. So for the engineer designing the equipment, the question is "What is the goal here - to produce a system that reproduces the original signal as faithfully as possible, or to produce a system that sounds as pleasant as possible to the majority of people?". Two very different goals."
Julf, I respect your POV, but there is more at work here than the above. Standard sets of measurements such as those published at Hypex site do not completeley describe the (objective) performance of any amplifier. Noise and/or distortion under steady state signals are not enough to understand what may happen in circuit with complex and widely varying signals. Intermodulation tests with many different frequencies, and square wave tests at many different frequencies might be more illuminating as to what makes for differences in amplifier sound.
Personally, I am not talking about making an amplifier which sounds "prettier" (adding its own color). I am talking about making an amplifier which produces sounds out of a loudspeaker which are closer to real music.
While I find the NC-400 sounds very good, it does have its shortcomings as well. Images are somewhat hollow, they are well defined in a single plane, but lack in body. In real music, the image does not lack in body. Consider just a cello, in a moderate size room...
What I also wonder about, is why would any self declared objectivist think that THD measurements define amplifier performance? My understanding is that DBT testing has confirmed that humans cannot distinguish between levels of THD <1%! By that standard all contemporary solid state amplifiers would be perfect, and all sound the same. If we accpet that any of these amps sound different, we also need to accept that distortion measurements do not account for the differences in amplifier sound.