As per the ' sub woofer' argument, For my home setup, I do like to 'experience' my music, I am running a system capable of 5,740Watts RMS, it has (2) Dedicated 20amp 120 Circuits installed for the 6 Rack mount amplifiers. ( Yes I know at sustained peak it would trip the breakers.. Already been there haha )
I was not happy with the classic '.1' Sub channel setup, so I took my front Left and Right channels and actively crossed them to create a Left and right Mid bass channels that I am running 12's behind my screen with and JBL control series for the highs.
My low end has (2) 15's that run in mono, with a summation of all the low frequency from both channels. I do run 10 channels of audio for 'the movie experience' But do prefer my classic 'Stereo' for most Music listening.
Now I said all of that to say, the normal home theater method of rolling off the audio that is below 'directional' level works on paper, but at excessive volume levels the 'sound waves' hit you at set directions. without the Mid-Bass I could tell where my sub was in the room ever so slightly by the way it 'felt' not heard.
Again all this comes down to each persons experience, and everyone will have there own, but for my room and music choice I found I needed (2) levels of separation before I could drop to a 'mono' sub channel.
In the OmniMax Theater I service They have the (8) 18" Subs mounted centered in the sound stage directly facing the listener. the room is effectively 'dead' as in the walls are fully sound deadened and during the shuttle launch the full 15,000 Watts of sound waves hit you, and you can 'feel' where the sub is, even with your ears covered. A very cool experience. I will have to find pictures of the Sub, you can walk in the front port!