To my knowledge there is nothing that significantly contradicts the research or its methodology. Welcome to read anything that does. Still struggling to understand why some people find it such a surprising set of conclusions. Don't misinterpret my agreement with the Toole research as dismissing the possibility of other facts coming to light, I just dont buy into the audiophile nervosa of
"theres stuff we don't know", which is just a neat way of justifying any particular dogma. Until compelling contradictory information comes along I see no reason to disagree with the conclusion that people prefer neutral measuring speakers.
Specifically regarding the multiple subs, I have just moved to 4 subs after years of a single one. I have subjectively noted major improvements in the bass, which are confirmed by measurement. FWIW, I have noted no detrimental effects to stereo image. In fact one thing I have always noted with non-centrally located single subs (ie not in between the two speakers) is a slight "phasiness" to the low frequencies. This is now gone. That is just my personal observation, I don't expect it to be taken as fact.
I will read your link in detail later, but it seems a bit nebulous at first glance;
The current project here has already stressed the fact that localization performance is dependent on room topology and source/listener location1,2. If all these variables are not addressed, then it is impossible to develop a robust conclusion, hence the focus on developing a generalized theory in this work.
It must be stressed that the recommendation for 1.8 uncorrupted wavelengths for accurate
localization requires further validation.
...mmmm...interesting but come back when you have figured it out guys
. However in the meantime multiple subs definitely solve known, measureable and audible problems.