Well I'm pretty sure they dont test to this level. They do audio test in the real world and I'd bet no one on this board can hear the difference. Not to knock on the science aspect of it but if the difference is inaudible who really cares?
Yep - once you are past the threshold of audibility, does it matter?
To some degree, yes it does... it provides an indication of the level of engineering care, design hygiene, that has been applied.
Ultimately it may provide an indicator to long term reliability for this very reason.
But in a day and age when top performing chips are so cheap, it is sad to see that AVR's keep falling far from stat of the art performance.
In the 70's there were true state of the art receivers, and competition was fierce in that segment.
Today the receivers are focused on movies and effects, techno-wizardry, where often the whizz-Bangs are more important than delicate detail in a soft piece of music.
I truly believe that a great Music oriented receiver will do a better job with movies, than one that is purely movie oriented - music is a far harder taskmaster.
And perhaps THIS is the key to where AVR performance is at.
On the other hand - a device with 7 to 9 channels of amplification, 11+ channels of DAC, 7 channels of ADC's, sophisticated audio decoding and processing, and all of that for under $2000.... it truly is a spectacular deal all things considered! Still - they raised the price, while reducing the valye - that is sad.