I can see by the number of posts that you are fairly new here (not necessarily new to audio) so I cut you a wide piece of slack and give the you the benefit of the doubt. This topic has been kicked to death here and often gets so contentious people end up leaving the forum or throwing tantrums. We don't need any more of that.
First off, audio isn't the only place people want double blind tests. DBT's are the basis of most types of research where we need to remove the affects of bias. Bias comes in a number of shapes and forms and is particularly rampant in audio reviews and opinions. The Placebo affect and other forms of observer bias are two particular forms that can have a major affect on any sort of A-B test we may wish to do to demonstrate how great some component is in our audio systems. One of the few tools we have to get down underneath those things is a DBT.
One of the chief problems with DBT's is they are difficult to perform correctly, involve money and expense, and most of us forget some key aspect of bias removal and we really don't end up with a good result.
@shadyJ does speaker reviews (like subwoofer tests) for AH. Send him a note or ask him sometime how difficult it is to be truly impartial and how rigorous his testing method is. It takes him a LOOOOOONG TIME to put out a test. Not because running a signal to a subwoofer or speaker is hard. But to provide unbiased test results is hard work that takes a ton of time.
Many posters in the area of HD audio, or those who claim to hear differences above redbook CD quality recordings, provide no data to support such claims. They simply "hear what others can't" because , well, they have extraordinary ears. Where extraordinary claims are made (and hearing music outside the range covered by a CD qualifies) then some extraordinary supporting evidence should accompany the claim. Most of the time, it doesn't. Hence the disagreements (sometimes quite heated) over whether HD audio in all its forms really brings anything to the table we can hear.
One other thing I will mention that relates to this is the question "is it audible?" Can I hear it? Audio is rampant with statistics that would lead you to believe one product is superior to another. The problem is in many stats, there is no audible affect: you can't hear the difference. If you can't hear it, does it matter? This is particularly true in the claims of HD audio. There may be technical or statistical differences between a CD recording and an HD one. Are those differences audible?
I am old enough to acknowledge that my ears are no longer candidates to judge the "finer points" of audio discernment. I have been listening long enough to know good recordings and the differences a good recording makes. Good recordings trump media, equipment, room setups, and just about everything else.
I'm happy with that.
