I see now where you are possibly coming from now, Tim.
When it comes to discerning subtle differences in sound between quality components of similar specs, your audiologist wouldn't trust you after a few minutes and neither would I. It's not personal, I wouldn't trust myself either.
Hehe, you haven't seen me in action yet then. Perhaps after watching me, one would gain some trust

At many of the audio events I have hosted and attended, I have been able to discern quite a few barely discernible differences within many a rig. Rigs I am familiar with and ones I am not familiar with at all. Often times when I describe what differences I hear, the 40 folks or so in the room shake their head in utter disbelief or discount what I have to say as "I'm hearing things". After further explanations and playback, followed by more detail of what I hear, does it dawn on the listeners that what I have observed is in fact true. They just needed to be acutely aware of what it was that I actually noticed. Now with that said, there are some folks that just can't hear. Not that they don't
want to, it's just that they are incapable of doing so. Age, profession, how loud they listen, ambient noise, seating position as well as a
plethora of other things can affect this.
I was at an audio event about 4 or 5 years ago to where about 20 or so folks were critically listening to some jazz on an incredible set of tube amplifiers. I just so happened to walk through the room and I stopped to tell the folks that were listening that their was an issue with the right speaker, in the ribbon area. Many there laughed and told me I was crazy....until 5 minutes later, the speaker smoked a capacitor. Where did it smoke? In the ribbon section of the right speaker. They ended up repairing the speaker with a capacitor that had a value that was slightly changed from the original and asked me to give it a listen. I did, this time in the sweet spot. I had mentioned that "something" was missing in the upper frequencies of the same speaker. Their was a null or omission of a frequency that was very apparent to me but not to anyone else there. The mathematics proved that I was correct, though others there could not tell any difference.
At another completely separate audio event, I was A/B'ing my [new to me at the time] Rega Apollo against a friend of mine's extremely hot-rodded JolidaCDP. I preferred the hot-rodded Jolida but out of the 27 folks in the room, most could not tell the myriad of differences until I started getting into some serious detail about the differences I observed. Even then, some of the "ears" that were there still could not tell any change and their were some well respected ears there that day. I have helped out some audio companies that did not release the product(s) they had for me to offer my evaluations on just based upon what feedback I gave them so when I say I trust my ears? Well, I trust my ears.
I have been labeled a "GE" before by some. They could be incorrect, they could be correct. Personally, I do not agree. Personally, I just think I pay attention more so than others and they are just blowing smoke somewhere where the sun doesn't shine. Who am I to say? To be honest, if I am? It's not a blessing, trust me it's a curse. I wish I didn't have some listening abilities, life would be much simpler and my wallet would be much happier. The point of this whole diatribe is that I trust my ears and when it comes to stress while listening? I have none and personally I can't understand why others would have stress while listening. Whether it be blind, double blind, relaxed, informal, in front of a panel or in front of 40 people.
Things are what they are and observations, if one knows how to listen, do not lie. YMMV but for me, in my experience and throughout my audio journey, thankfully they have not. Perhaps that's why I feel no stress while listening. Besides.....it takes the fun out of it and if you aren't having any fun? What's the point?
Tom