"...why do so many HEA hobbyist talk theory without any, or very limited, empirical testing or experience?"Michael Green,
I think I may have an answer for you on this one.
For most of the hobbyists, this is hobby. It is not work. Most do not have websites dedicated to it or businesses to run associated with it. That means, they have no time, and/or probably means, to do testing of everything that might be out there or that they may even come up with themselves. They prefer to conduct reasonable thinking before undertaking. It does not mean they are faking anything, but that they are economical with their time and resources. In a simpler way, that is the way most of the science is practiced these days. That is the way that helped most of us survive to this day. Think antibiotics, food, transportation, you name it. People who invented or designed those things were hardly fakers. You may be looking at this hobby from a different perspective. Some might say that you are calling for a wasteful way of getting to some goal. The approach you seem to advocate may not be wrong, but may not be completely right either. It depends on the circumstances.
Phil Collins' studio builder's response about this thread is about right and this thread, as useless as it actually is, has become amusing like some kind of electronic zoo.
However, on a much more serious note than anything that has been written here, it may not be a bad idea to remind ourselves that this hobby may not be completely benign. Having a studio does not seem to help, either.
https://www.healthyhearing.com/report/47742-Musician-hearing-loss-phil-collins