As before, you seem to be replying to something other than the text I actually wrote. Something can be "low fidelity" but subjectively enjoyable.
How long are those wavelengths? How big are the name-brand baubles you are using to manipulate them?

The answers are, respectively, more or less "very long" and "not big enough," if you were curious.
The "big pile" of subwoofers (interesting metaphor but factually incorrect, because to be useful the multiple subwoofers need to be distributed around the room as far away from one another as practiceable; if they are in a "big pile" they sum to effectively one subwoofer) is deployed not to smooth response in the first-mode region (below about 40-50Hz in a "small room"). The first-mode region is best addressed with global EQ for all subs, because the modes are so sparse.

You wrote: "Any home audio system that does not employ multiple subwoofers and suitable EQ based on in-situ measurements is a low-fidelity system. Period. Doesn't matter if the speakers are some cheap full-range deal or TAD Model Ones."

That sentence is a big pile of bullshit. That's the text that you wrote, that's what I'm replying to. "does not employ multiple subwoofers and suitable EQ " vastly overestimates the importance of the 25-40Hz region which is actually fairly moderate in overall importance, in the grand scheme of things.

A typical 2" trap stops being effective around the 250Hz region. A 4" trap placed flat on the wall can still manage NRC 1.0+ down to about 150Hz. Putting them in corners with an air gap behind them makes them far more effective, they can manage NRC 2.0+ down to 100Hz, and are still absorbing (0.80) down to about 80Hz. Below that, you really need targeted traps. A standard 8" trap is far more absorptive at around 80hz, but still ineffective below that. Again, targeted traps work differently than traditional broadband absorbers and are much more effective than you seem to think. Whether you think they are "ugly" is completely irrelevant.

I'm really glad you're so in love with your multisub arrangement. To suggest that it's "required" for high-fidelity sound in a room however is a bunch of BULLSHIT.

Have the two of you forgotten that there is more to hi-fi than just bass reproduction?  I think sometimes audiophiles get so lost examining the texture of tree bark they forget how to look at the forest.

That's what I was trying to get at when I said that plenty of people are perfectly happy with monitors that have little to no deep bass extension. DS-21's response was basically "those people are ignorant fucks."

Hence we're back square one with headphones! Kidding, I have a feeling my presence in the thread is not appreciated so I will sit back, watch, laugh, and maybe learn a bit about the advances in room acoustics over the past 10 years

I think it comes down to what high-fidelity means. I know many an audiophile who feel that accurate 20-20k reproduction is a basic tenet of high-fidelity. Perhaps Jay's statement on "low-fidelity" was a bit too strong or exaggerated. Although what Jay says makes sense to me from a logic and intuitive level:
LOL, it's probably cheaper (but more work) to build /x-over/plate amps/subs than buy bass panels which are only marginally effective at lower frequencies. The cost does start adding up over multiple panels.

Perhaps some do, but IMO 20-30 in particular is of marginal importance at best vs FR overall, is very difficult to get perfect, and is not worth spending tons of cash on. If you want to buy a bunch of drivers, boxes, and plate amps or amp/eq combinations and build them all, be my guest. Maybe if you do it 100% DIY it won't cost a fortune. Commercial subs OTOH that are any good will cost you a minimum of about $1000/ea. The big RELs and JL Audios are triple that amount. And you need what, 3? 4? A targeted 10" membrane bass trap will cost you $200-250.

One of the best systems I've heard in recent years was a pair of NOLA Micro Grands in a professionally treated room. The NOLAs are all out of ideas by 35Hz. To call that "low-fi" is idiotic.