Jtgofish,
"If you have to make physical changes which take more than about 20 seconds you cannot recall accurately the sound prior to the change.That is as long as our sonic memory lasts.
You are just being silly or you have terrible hearing.
By memory I can tell you on any number of cuts where exactly in the soundstage that the guitars, cymbals, typanis, voices, etc. are located with perfect accuracy in relation to the furniture, paintings, windows, speakers, etc. in my room. And I suspect most members here can do the same thing with their systems with music they are intimately familiar with.
Oftentimes a cable change, component change or speaker placement change will definitely alter the soundstage placement of instruments or voices that a three-year-old would notice. And if your system requires that you need to keep your head in a vice because the sound changes that dramatically; you need to rethink your choice of speakers -
"And as I said shifting your head position is likely to change what you hear so unless you have some sort of head clamp then you cannot asses changes properly either."
I would not argue that my aural memory may not be able to recognize or differentiate tonality or pitch changes very readily after a time, but I suspect many musicians might be able to due to their trained ear.
But I can assure you that the glare that was present before changing my preamp isolation is now virtually inaudible. Things like soundstage width, heigth, depth, muddy bass, glare, brightness, etc. all can be easily remembered from one listening session to another. Are you really trying to tell me that you don't think you could recognize glare, hardness, brightness (or however you would describe it) and then not hear the difference if it was absent?
A classic example of aural memory is the accepted "truth" by virtually all accounts that most systems sound better at night due to cleaner power. If we couldn't remember more than 20 seconds how our systems sound then we would never have the experience that our systems sound better at night. We simply couldn't remember the more dry, flat presentation of the daytime as compared to night.
And if you can't remember how a system sounds longer than 20 seconds, you may as well by a Bose surround system and be content. Using the 20 second rule, you should be able to play your current system and 20 seconds later play the Bose system and not tell them apart assuming volume levels are the same.
Hey, I'm ecstatic with what I am hearing since I altered my preamp isolation. If I am simply delusional, so be it. I'll just continue to enjoy my delusion.
