Will I benefit from a subwoofer with 20Hz speakers?

@erik_squires You owe nothing to anyone or me. Your voluntarily service to the audiogoner in the community is beneficial as I have complimented previously. However, when you make such a strong/powerful claim and try to maintain the credentials when others challenge, the burden of proof is on you. It is a reasonable doubt that what you have measured is one thing but what is actually heard is another. It is your decision to do what I have suggested, which is another way to disprove something that I and a circle of friends of mine don’t believe achievable. We all do not believe will be so "lucky" as you are...

Oh, BTW, last time your advise toeing speaking in front of MLP and I reply with the shrinkage of SS as a result, you ignore too.  Is it another way of yours admiting something you have advised is wrong?  Ignore again.  I don't care but just wish get some mindful message across so others will not follow the wrong footstep.

It depends.  Have you measured your respone with pink noise at the listening position? 

Subs have flexible placement and may be able to boost the low end and fill some holes in the bass if needed.  

If your response is smooth then I would not add subwoofers.  It takes a lot of work to get them to sound perfectly integrated.  

You have more than enough amp power to give your speakers a full range sound.  

A great full range speaker is the best way to go for me. 

@erik_squires ,

You have responded well to the OP's original concerns, and I for one appreciated the dialog.  You've not only laid out a reasoned approach for assessing one's existing setup, but documented some very economical tools for doing so.  

It makes perfect sense in these cases to collect more data and learn more about your system/room before laying out $4K or so in subs.  I for one would definitely go this route.

The notion that you failed to make your case - for questioning the accuracy of published speaker ranges without also considering room effects, - is ludicrous.

You gave some good examples, including specific comments on OPs speakers. 

Even Hans Wetzel's review of the Cabasse Pacific 3 mentioned by @dmilev73  - but apparently not read by the skeptics, alluded to the same point:

"The speaker’s claimed 41Hz lower limit must be an anechoic measurement; with room gain, I’d be shocked if they didn’t have solid output down into the low 30Hz range, possibly even the high 20s."

Please keep the great comments and ideas coming!

Sandstone

My point, and I made it after my head got hot, is that rather than demand I do more work, others should instead follow the discussion and contribute their own findings.

Honestly, I am super curious about seeing data from audiophiles comparing their speaker’s published spec and in-room response. I would learn a lot from that.

Very little benefit, IMHO, would come from me recording my system, and honestly, I don’t have a lot of time and energy for this. The more others contribute their experience the better the elephant will look.

I am by no means anti-sub.  I love subwoofers, but consumers should be clear-eyed about where their system is starting from and what problems or benefits they hope to achieve.

I have _never_ seen anyone regret analyzing and treating their room before adding a sub, but I have seen some decide not to sub.

Do most audiophiles not understand that the published speaker specs are in an anechoic lab unless otherwise stated?