I largely agree with and affirm the points made and conclusions reached by Wayne.

The only exception I will respectfully take is that I believe a single test position is not sufficient for subwoofer signal modification. While the lower frequencies do not provide perceived directional cues to the listener, bass frequency ‘standing waves’ in a room with mild, moderate, or strong resonances make reliance on a single test point a poor choice.

Let’s say that a given room has a large resonance response at 48Hz. There are still places in the room where, by moving about with one ear covered, one ear open, or with an SPL meter, 48Hz is perhaps 10dB over the average and other places where 48Hz is 10dB under the average. Unless the measurement microphone is placed in a position where 48Hz is at an average, the adjustment for 48Hz will be off. But then if the measurement microphone is in an average position for 48Hz, it doesn’t mean it is at an average position for all other subwoofer frequencies. Granted, there are test signals that are better to use than sustained sine waves, but normal source material will have some frequencies sustained for long enough periods to result in standing waves and resonance in the room, so it is good to 'observe,' among other tests, what happens when standing waves are present.

It is not realistic for me or anyone to expect a flat and properly time-aligned response everywhere in the room no matter what forms of analysis and correction are applied. While this would be ideal, I cannot afford the pursuit of that goal to the nth degree of what is actually possible. But short of that nth degree, I can still measure and take note of differing response in different areas of the listening environment and make reasonable adjustments to: the signal (including internal EQ or external devices like the SMS-1, if present), the placement of transducers and room treatments. Personally, I would never rely on a single, or even just a handful, of measurement points if I want the best overall experience for all listeners present.

If the signal modifying equipment allows for several presets, one could have a saved setting for the ‘sweet spot,’ another for an ‘alternate sweet spot,’ another averaged for ‘small group near the sweet spot,’ and yet another for ‘best average for a large group.’

Enjoy finding what works for you!