Why the fascination with subwoofers?

low E on a 4 string bass is 41hz.  A lot of speakers can't even go flat to 40hz.  Low B on a 5 string bass is 31hz.  Lowest frequency on a piano is 27.5 hz. 

Ive never hooked up subs and dont feel I’m missing anything. Different speakers bring different results and it just seems somehow obvious when any part of the sound spectrum is not quite right and time to move on to another speaker. Had some Monitor Audio one time and dont get the attraction there. In my system at the time at least. Thin and a bit etched. My Harbeths are all around a good sounding speaker. I suppose for home theater some may want that all enveloping sound of the lower frequencies ... I never got into home theatre,, Just doesnt interest me but can understand why some do.  @kink56   what you are saying  does makes sense and I have to admit I've always wanted to check it out.   Dont know that I will anytime soon.  

I have a pair of 12" sealed subs playing mono and been wondering about adding one or two more with the goal of flattening at the main seat. Would love to know your take on this.

I'd give it a shot. I don't use the Swarm but if I had it to do over that's the route I'd likely take. Duke is working on a sub system for me though- one that is integrated into a coffee table. It will be used to break up the standing wave in my room.

1 - Agree that subwoofer integration in a system can be difficult/problematic

2 - I'd rather have a speaker that goes accurately down to 40 than a full range that is less accurate. Martin Logan has achieved integration of a cone woofer with an electrostatic panel at least once - the original Monolith, and it was hugely expensive and still only went down to 35 hz. I prefer my CLS, which are a bear to drive (~83 db/1w) and dip to 1 ohm, even though they are 3 dB down at 40 Hz - you won't find a more accurate speaker

3 - I have other speakers that integrated a subwoofer, with separate powered crossover, separate amps and push pull drivers that are 3 dB down at 23 hz. They were expensive in terms of cost and in terms of requires amplification.

4 - I also have speakers in my main system that are capable of low bass without multiple amps etc. - 20 hz 3dB down  Ideal, expensive of course, but a complete solution without worrying about system integration.  I use them as the main speakers for video as well as the only speakers for audio, but I also have a couple of powered subs that are 3 dB down at 16 hz used only for video.

Out of curiosity, I hooked them up in the main audio system to see if there was anything missing, and can say that  with few exceptions (organ recordings that have content from the low C pipe (32') of a full sized organ, which is 16 hz, or a rendition of the 1812 Overture using real cannon fire) You aren't missing anything if your speakers can go down to 30 hz or so (remembering that you only hear down to about 20 hz and below that you are feeling it).  Bear in mind that the lowest note from a bass guitar is 41 hz, or from the low A of a concert grand piano at 27.5 hz.

My conclusion - by all means play around with subwoofers if it pleases you, but IMHO it is better to have an accurate system that won't reproduce the very lowest notes than one that will, but at the cost of poor integration between sub and mains.

Final comment - I find it amusing/ironic when stereo addicts worry about having speakers that will accurately reproduce notes lower than is contained in 99% of music  but end up buying what are essentially low base rather than true subwoofer add-ons (and some of them are listening to ipods most of the time).

This thread is well worth reading (this subject keeps coming up again and again).

https://forum.audiogon.com/discussions/hz-how-low-for-full-range-music