I caught this thread a little late,so I apologize if my point has been mentioned...
From my experience(and I'm sure others)the "dead quietness" issue is "dramatically" affected by the actual room itself!!
This is emphasized whenever I make my trips to Brooklyn,NY where two audio pals live(Sid and Ed).
Both have "dead quiet systems"...BUT... they both have different listening room "quietness levels"!!
Sid lives on a quiet block(like me)and the noise floor of his superb room allows for ALL the detail,and tonality of his "amazing" LP collection to be appreciated!Except for the occassional garbage truck passing by -:)
Ed lives in an apartment building,and although on the 22nd floor,the highway noise below,coupled with a noisey building/neighbors absolutely "devastates" a decent listening session!His magnificent/dynamic/dead quiet componentry is wasted...."during the daytime"!
In truth,from what I observe,he is almost unaware of the problem,because he's lived there for SO long!
At night it is a different story altogether.Then one can appreciate the "almost dead quietness" of his set-up.
I am lucky(big time)to have a purpose built dedicated room,which is basically adjoined to my home,on one side.This means I am not bothering family members with volume,and the closest neighbor is 100 feet away.
My noise floor is SO low,my friends kind of make fun of the situation,but this is definitely useful in getting the best from a good set-up.No extraneous noises,and easy to listen for problematic system voicings.There is a downside here....
There IS a real problem(not kidding,actually)for "this" kind of low room noise floor...
You cannot tolerate "any" additional noise,after living in this type of situation,so something like a "tradeshow" is torture!!One can get a bit too picky quite easily,but it's easy to get used to....Those of you in similar situations know this already -:)
Best