You made your point. However, I disagree. Your calculations and expectations are exceedingly simplistic and hence misleading.It's a great speaker, but it depends on the requirements in order to assess whether it's capable, or not.
If the design objective is reaching THX refence levels at 20Hz, the Salon2 would be incapable of that (on its own).
THX calls for speakers to be capable of 105dB peaks, and subwoofers be capable of 115dB peaks -- at the listening position.
Factors that were considered are the Salon2's published specs of 86.4dB@1m efficiency and -6dB@20Hz, plus factoring in a reasonable listening position that's likely 4m rather than 1m. Doubling the distance reduces SPL by 6dB according to the inverse square law, so factor a -12dB attenuation should be applied based on doubling the 1m distance twice, and then granting a 3dB bonus because there are 2 sources.
My math says that's about 8000 watts to coax 115dB of 20Hz energy at a 4m listening position, but as speakers they'd only need about 500watts to reach the 105dB objective for those frequencies.
watts efficiency 4m distance -12dB two sources +3dB 1 86.4 74.4 77.4 2 89.4 77.4 80.4 4 92.4 80.4 83.4 8 95.4 83.4 86.4 16 98.4 86.4 89.4 32 101.4 89.4 92.4 64 104.4 92.4 95.4 128 107.4 95.4 98.4 256 110.4 98.4 101.4 512 113.4 101.4 104.4 1024 116.4 104.4 107.4 2048 119.4 107.4 110.4 4096 122.4 110.4 113.4 8192 125.4 113.4 116.4 16384 128.4 116.4 115dB target
All that said, if one or both of them are positioned such a 20Hz null exists at the listening position, then this goes from incapable to impossible... and illustrates the point that was made earlier -- that optimal speaker position isn't always optimal for producing bass, and that subwoofers are useful tools to keep in our audio toolboxes.
Have a good day.