Hearing is not just dependant on the "ear". While most hearing issues can be blamed on the "ear", the sensation of aurality is complex. After the "ear", there are numerous pathways that must work in sync. There are numerous nerves that must come together as one and then some cross over from one side of the brain to the other. There are numerous very small nuclei within the brain structure that are then necessary to interpret that data. This does not even include the influence of ingrained memories within our neurons. All of these potential pathways can be affected by microvascular disease, mineral and vitamin fluctuations, trauma, medications, memory loss, etc.
As an analogy, consider the sensation of taste. I am now 50 years old. When I was 30, I sought out the most spicy food imaginable. Now that I am 50, that endorphin rush is no longer worth the pain that it invokes. Same for vision. I used to be able to drive through the night taking my family on vacation. Now I find it difficult to drive from my house to the corner store 1 mile away at 10pm while raining. To much glare!
For some of us, the sound is to dull or maybe there is to much glare. The audio components that we own or test, therefore have multiple pathways of influence on our "hearing" system that can make our perception of sound from one person to the next different enough to be enjoyable or not.
For instance, I find the hum of our home furnace in the winter time very soothing. It brings back memories of sleeping over at my Grandfather's modest house while I was a young boy. My wife wishes we had electric base board that didn't make any noise.
After all of that, I believe the most important link in the chain is ingrained memory. Such that, I think sound which is pleasing based on past pleasure will likely be pleasing in the future and not so dependent on the price of the system that it is played through. Of course, I am not saying that listening to Ravel's Bolero is as good through my cell phone as it is through my main system. The "ear" obviously is the first link, but the end interpretation is much more complex.
However, the fine tweeks that are so often discussed here are really quite impossible to categorize as better or worse because we all interpret the data slightly differently.
Thanks to Eric for getting me to think about this again. I shall trust my own ears when it comes to hardware. After all, my "ears" are the ones hearing it. All the while, recognizing there are a lot of great opinions amongst us that may eventually influence my perception.
Rich