Just looked at the current discussion in
http://www.audiosciencereview.com/f...wanted-proof-of-multiple-subs-and-sub-eq.185/. The trouble is, where the severe mismatch with me and other is, is that I haven't heard a shred of music on a system in the last 30 years that demonstrates, for me, the importance of that type of investigation, and refinement - for achieving the illusion.
The most amusing "proof" was the Philips setup - employing a decently competent, single subwoofer for everything below about 150Hz - at times it died, gave zero output; because of of a rushed tweak, too much moving of something, a connection would come adrift - solder has no mechanical strength - and there was zero true bass! And we didn't pick it!! At times several albums would be played, until I suddenly registered, hey, there should be more bottom end here - and realised there was, in fact, none!!
What was happening was that the rest of the spectrum was presenting such a convincing picture that our minds were reconstructing that necessary bass filler - is how I would explain it.