Why the obsession with the lowest octave

Where are people getting this sub-harmonic talk. Yes, string instruments can produce sub-harmonic sounds, but it is not a commonly used technique and it's virtually never written into compositions. Harmonic overtones are always present in acoustic music, sub-harmonics are not.

"Grandma's Hands" was recorded on a suspended wooden floor which is being excited by the foot tapping of the singers. It's a common effect in recorded gospel music. It's debatable if those sounds are part of the performance or are they in the class of falling mic stands, A/C rush, passing subways, page turning and fret scrapping, in other word noise. Although on tunes like the Supremes "Where Did Our Love Go" the floor effect is prominently featured as part of the rhythm track.

Another thought with a full range speaker is that if the speaker is capable of reproducing extrememly low tones (the same goes for the extreme high tones as well) then the vast majority of music doesn't require the speakers to work at the max capacity. I think this is applicable to just about all audio equipment. You wouldn't want an amplifier to be driven maxed out. This would only apply to a subwoofer in the sense that it can reduce the low frequency requirements on the mains. Having a tweeter than goes well above the audible frequency range just allows a better reproduction in the range that you can hear.

"Having a tweeter than goes well above the audible frequency range just allows a better reproduction in the range that you can hear"

Not necessarily - it might distort more at few kHz range.

Of course, having the ability to deliver very deep and powerful bass is a big advantage. I just think that, given the usual constraints of size, power requirement, and BIG dollars, there are tradeoffs involved. There are tradeoffs for ANY aspect of speaker performance. The choices one wants to live with depends on taste, type of music, etc.

For example, unless one is talking about a very well engineered active biamp or triamped system, trying to achieve really deep bass using low-powered tube amplification is extremely impractical (look at some of the as-big-as-a-room bass horns of some Japanese systems). But, if you have heard what a really good SET amp can do, trading off some bass capability might be your preference; it is a matter of taste.

I actually have speakers capable of reasonably deep and powerful bass (it has two 12" drivers per channel), but, my chosen amp really cannot deliver room shaking volume. What this combination offers is doing almost everything else right at a comfortable volume level. It is a big system, with a "big" sound, just not a super loud system. I don't use it for home theater, so I don't need things to shake when it plays.

I have heard many speaker systems with full range bass capability (e.g., Wilson MAXX 3), and certainly they do deliver in that respect, but, I have heard few that, on balance, I would prefer over what I have (and those were also not particularly big in terms of bass performance).

Can't say for others but I "get" the harmonic content from mathematics. You guys are all free to believe what you want and setup your systems any way you see fit.