http://www.webervst.com/fm.htm
 
 

Depends, does the tone control go to -11?

Depends on who's speaking. It's all about the bazz.

The link in the OP was from a speaker manufacturer and is useful while explaining one reason why speakers "sound different" at different playback levels.
 
This chart has the relative loudness expressed as SPL...
 

 
... and it would seem to provide all sorts of useful info to anyone hoping to listen to a wide bandwidth of sound at what might be described as quiet listening levels.
 
 
 
It might also suggest how proximity effect can be beneficial to anyone recording a wide bandwidth of sound at what might be described as quiet listening levels.

Mike this is a topic that I have in the past called very subjective. I have learned, the hard way, there is no such thing as " bedroom" volume. I have come to realize that I like the feel of the air moving around me when I play.

So what I "feel" is ummph maybe different than your "feel." And I can say with almost certainty that it is not what some call "bedroom" volume!

Though I wonder what that response curve would look like with those half watt, milliwatt amps?

 
Are we having phon yet?
 
 
 
 
 
 
 
 
 
 
 
Ha, I crack me up

Good one Steve!

well,
in terms of recording, 
the PROXIMITY effect can be used to taylor the eq of a particular sound source,
especially miced guitar cabs.
 
used properly, you can add lots of 'oomph' without a lot of volume or speaker excursion.
 
 
but to get the meatiest sounds, volume does play a part.
 

To be serious, it also depends on the type of speaker system you own.  Traditional closed box and ported speakers will lose bass frequency response at low levels.  Switch to a transmission line design like PMC monitors and you will hear a relatively consistent bass ummph even at low levels.  

Depends on how close your ear is to the sound.