Why are digital streaming equipment manufacturers refusing to answer me?


I have performed double blind tests with the most highly regarded brands of streamers and some hifi switches. None have made any difference to my system on files saved locally. I have asked the following question to the makers of such systems and almost all have responded with marketing nonsense. 
My system uses fiber optic cables. These go all the way to the dac (MSB). Thus no emi or rfi is arriving at the dac. On top of this, MSB allows me to check if I receive bit perfection files or not. I do. 
So I claim that: if your dac receives a bit perfect signal and it is connected via fiber optic, anything prior to the conversion to fiber optic (streamers, switches, their power supplies, cables etc) make absolutely no difference. Your signal can’t be improved by any of these expensive pieces of equipment. 
If anyone can help explain why this is incorrect I would greatly appreciate it. Dac makers mostly agree, makers of streamers have told me scientific things such as “our other customers can hear the difference” (after extensive double blind testing has resulted to no difference being perceived) and my favorite “bit perfect doesn’t exist, when you hear our equipment tou forget about electronics and love the music”!
mihalis
And just to highlight. With those memory patients, the preference test is highly reliable (defined in testing science as a consistent, repeatable judgment). Their performance on the identification test is completely unreliability (i.e., no different than chance). You do not need to be able to say x = a to make a reliable preference judgment.  I suspect if you instructed people to base their identification judgments in an abx solely on preference they'd do significantly better.
Your example is an absolute identification test. As noted this is not applicable to the discussion. You seem to be missing the point.  If you have AB and X. And have a definite "preference" for A, then when x=A, that preference should replicate.  You try wine A and B side by side. You claim you prefer A to B.  Now I give you wine X. Do you claim you prefer it to wine B? If so, it must be A right? What if it is actually B?  That means your "preference" was random.

They have studies with patients who have zero long term memory. Every day they fail an X test by failing to identify people with whom they've interacted with repeatedly.

  I suspect if you instructed people to base their identification judgments in an abx solely on preference they'd do significantly better.


Actually what results in better ability is training in the characteristics of differences. The natural tendency is to rely on "preference", which is very fickle.

Nonetheless, they form adaptive preferences for these individuals based on whether those past interactions have been positive or negative.


Which would require learned neural patterns. This is not related to directly to ABx and more related to why blind testing is necessary to ensure the learned neural patterns for looks are removed from sonic decisions. However as applied to ABx, those learned neural patterns should trigger the same for A and for A=x, as opposed to B.  It is also why training improves ABx as you develop additional neural pathways for characteristic detection which is what preference is. 


When people get the X test with audio equipment I suspect many are trying to figure out if the treble, bass, image depth, tonality, etc. match A or B, not asking themselves how much they like the presentation and then seeing if that preference is closer to how they felt when they listened to A or B. Of course we’ll never know if that’s true because unfortunately I don’t run an audio testing laboratory.

And yes, there is learning happening in the memory patients, but the area of the brain that makes explicit identification judgments does not have access to it. I’ll also note that when they fail to recognize a previous acquaintance that new/old judgment is even easier than matching to a particular object as required to succeed in ABx. Despite utter failure of explicit identification, the preference system chugs along just fine, leading to adaptive decision making.

This dissociation is why it is incorrect for you to state that, "if you can’t match A or B to X, then you can’t tell the two apart and you hence have no preference as you don’t as actually prefer either."

Anyway, it’s clear you’re going to continue to believe that matching judgments are the appropriate way to do A B testing. And that’s 100% not how I would do it if I were optimizing people’s decision making. It doesn't matter if you can pick your stereo equipment out of a lineup, it matters whether or not you like it. So be it...
And it is quite clear that you will continue to misunderstand and misstate the processes involved in an ABX audio test, even though you admitted you really don't know what happens.  But, nice to state, effectively that "we'll" never know because "you" don't run an audio testing laboratory. I am sure no one who does this style of test has any experience in testing human perception ....

It's rather "interesting" that "memory" or pathways, or whatever, are good enough to "remember" well enough to know if they prefer A or B, but not well enough to remember if they prefer C more than A, or C more than B.  That is what you are stating even if you think you are not. 


You whole argument is based on assuming a process that you admittedly don't know, and then assuming it must not be the one you feel it should be or would be more successful. That is bad science.


As a counterpoint, people who are not "audiophiles" have been shown, several times, to be more adept at detecting minor differences when they are trained, i.e. taught what the differences are likely to be, and given examples. They create the appropriate pathways for detection of differences.  To be clear, more adept than "audiophiles".  Based on communication of audiophiles when they compare cables, certainly on here, I would say that preference is exactly the method they use, or at least claim to.

Here is the thing. When comparing two of anything in audio, like in AB or ABX testing, the descriptors are invariably related to preference. More natural. Improved soundstage. Pinpoint imaging. Tighter bass. Sweet mids. These are comparative descriptors, not unary descriptors. That indicates preference.


Let's not forget that while double blind ABX testing is considered the gold standard, there is no more success achieved in AB testing either, which as per the used descriptors, are preference related.
audio2design
... double blind ABX testing is considered the gold standard ...
Not everyone shares your measurementalist’s belief that ABX is the "gold standard" for evaluating audio equipment. Not even close. It appears that really upsets you.

That doesn’t mean that ABX is useless, of course. But it’s just a tool - a single, solitary tool.