You may want to refer to the 30k thread for answers to the audio gain aspects of antennas
IMO, that thread is full of misinformation. I go along with guys opinions however, unless I can make some reasonable argument that differs.
Mac I can only guess what goes on with you at your location, but from the image I get I see you high up in God's country in a very rural setting and in your own words you tell us that you don't have any, meaning zero, local traffic or contacts and only DX when it rolls, so how is it possible that you could even tell if one antenna sounded different from another? Or, am I misunderstanding what you're suggesting? I've said before that DX is not a reliable source for testing the gain differences between antennas, and I think that 399 confirmed that idea in his report of his contact with me a while back when he saw no difference in signal, but a difference in audio. So, what are you using to make your judgments on any of this?
I mentioned at some point here on the WWRF, that IMO most are not likely to notice such a distinction unless they can hear it from one of their regular contacts that also has two antennas up, side by side and that is capable of producing such a response. I believe your impossibility argument idea likely goes back to the claims made by JoGunn in their advertising and the criticism they get for talking about audio. I might agree that JG overstates most everything they claim about their antennas, but that does mean that audio differences are not to be noted in on-air observations at times by others.
When I hear guys asking and giving signal reports on the air, I often hear them make the statement that the audio is such-and-such...in addition to the signal report. In such cases, I assume they too are hearing something that is either different or the same with the contact, else why would the mention the audio, right?
Since you raised the issue, why don't you pick out a particular post on the 30K thread that you find most informative and we can discuss it?