very very few mains will put out full volume 20 hz bass at the listening position
Well, depends what you mean, but room gain is quite powerful. Take a look at what my two-way speakers with a 6.5" woofer can do:
https://speakermakersjourney.blogspot.com/2020/01/the-snr-1-room-response-and-roon.htmlI’m not saying my speakers’ are exceptional, I’m using them as an example that most audoiphiles don’t know how much bass they have, which then leads them down several paths to disappointment.
The -3db point of any speaker is a very poor indicator of how deep bass will go, or how it will be perceived in any given room.
Best,
Erik