I believe that most of the question here, mine included, is not about proving that hiyaw exists, but asking for an explanation on what it is exactly. Those who support hiyaw cannot seem to agree on what it is, based on what I have read in this post. It is like an abstract painting being interpreted by two persons, both saying it is beautiful, but interpreting it differently.
I do not agree that food is a good analogy. We use our sense of taste to judge food. On the other hand, a guitar is an instrument to create music. Music is appreciated by our sense of hearing. Music can be recorded. You cannot record taste.
You cannot record taste, yes, but it can be recreated consistently by a good chef. With recording however, and this is independent of the hiyaw issue, it is not a facsimile, however way you put it. You can only recreate the almost exact sound of something in a sound laboratory, which is ultra dead, and of course at the expense of overtones and other reverberations. If you've ever talked to a recording engineer, you will know that a half inch movement of a microphone can change a recorded sound drastically. That is why in the drumming world, where cymbals are usually chosen by their acoustic, unmiked properties, we tell buyers to always check them out in an ideal room with their preferred sticks. Likewise if hiyaw did exist, definitely it wont get into the recording.
I used food as an analogy because like fine instruments, it has a certain quality that makes them better than the rest but you can never really point out what the hell it is (just like the hiyaw issue). Parang yung pandesal sa kanto samin, pare-pareho lang naman ang recipe ng non-sweet pandesal, pero may ibang sarap yung pandesal nila, using the same ingredients and methods (I asked, it's the normal TESDA recipe).
Yung hiyaw na issue na to feeling ko parang Stradivarius to eh. People claim that the Stradivari instruments have this quality that cannot be pointed out (like food, my preferred analogy). Violin construction is not wildly different, and tone woods in that era aren't chosen as precisely as we do now with fine measurements of density, grain, etc. So it can be said that any improvement in tonewood or construction is not exceptionally different, and yet it has a hiyaw-like reputation. But then several double blind tests have revealed that one cannot distinguish Stradivari from violins of different vintages.
I think a double blind test is in order, of course kasama si firemodel, another person who believes in hiyaw, a professional electric guitarist, and a professional electric guitarist who is also a tone geek. All guitars (hopefully the same shape) should be set up to what FM55 thinks is the closest it can get to best, then all four play the guitars with the exact same amp, cable, and room. then all will test the guitars blind, and 1. say if the guitar is the hiyaw-claiming guitar, and 2. if they think they can't tell.
EB na to!