My 2 Cent:
Woofer companies mix
A)
I currently only use two subwoofers, and since the sub output is in mono, you need to pay attention to where the crossover frequency of the woofers to the main speakers is.
This also depends somewhat on the genre being listened to.
If the genre is more DUB/techno or similar, a frequency < 64 Hz is a no-go, and in songwriting, well, and classical/jazz live, it's also a no-go.
B)
Strictly defined, ONE woofer is already close to a no-go... Unless it only serves the range < 40 Hz
I always find it surprising when I ask what frequency the current bass is and what the answer is.
It is usually located deeper than it actually is.
For two subwoofers, i.e., outside of a dipole system, the option is to place one between the main speakers and the other in a higher position at the back of the wall to handle the room gain.
One between the main speakers, the other in a higher position at the back of the wall, which controls the room gain.
However, I doubt that the Wiim Sub DSP can handle this.
So back to A.