A good article Spoiler. I'm surprised JohnK had not posted the link more quickly. Though articles like this can be found around written by audio gurus (such as Masters, Loftt, Toole), i have yet to see a SINGLE similar article of a double blind test where someone could tell differences between quality made amps and brand name receivers (or similarly gauged boutiqe and 'common' gear).
I only ever read about the subjective rantings as to how those who want to see the science and numbers behind the conclusions have never:
A) heard a really good amp/cdp/{insert gear here}
B) must have poor hearing
C) are using a switcher that is corrupting the signal
etc.
etc.
etc.
etc.
etc.
etc.
etc.
etc.
etc.
etc.............


Anyone who doesn't have their own A/B switcher before stating such subjective conclusions as fact are being hypocritical. They want 'naysayers' to supply truth and fact but the 'believers' never supply any of their own beyond "what they swear they heard".
Anyone who has ever wondered how the magic trick was done knows how easy it can be to HONESTLY fool the human senses. What i fail to understand is why the 'believer' camp finds it so hard to want to try an honest A/B blind test to find out for themselves what is the truth.
Anyone who has had the opportunity to do this type of switching while auditioning at our home has fast become a believer of a different theory.

If two quality amps sound different it is because they were designed with some sort of filter, are not functioning properly, or they have a pathetic power supply. If an amp measures a frequency response flat across the spectrum and its power supply is not taxed, then once again i ask, "explain to people the very reason for how it sounds different"
Still waiting for a non-magical explanation and i've been on these forums now for oh about 5 years...

"Those who preach the myths of audio are ignorant of truth."