Stereo subs make a difference?
Answer: It depends.
This answer can be found in multiple places. Here’s one.
"While low frequencies are less directional, and the direction of a low-frequency sine-wave point-source may be less perceptible, critical to fine music reproduction are low-frequency interchannel phase differences present in true stereo recordings. When reproduced properly with stereo subwoofers (or two full-range speakers), these phase differences are critical to reproducing the sound space of the original concert hall.
Critical even to casual listeners is that if you sum the low frequencies of true stereo recordings into mono by using only one subwoofer, low-frequency interchannel phase differences partially or completely cancel each other, reducing or eliminating low-frequency output levels!
Try jamming a stereo bass signal through one mono subwoofer and you lose a lot of hall ambience as well as bass level.
True stereo recordings are usually classical and other proper acoustic recordings made with pairs of microphones. Most "stereo" pop and jazz recordings are really just multi-miked mono, with each mono mic "panned" someplace between left and right. Pop recordings rarely have low-frequency interchannel phase differences, although they usually have bass information panned one way or another that also should be reproduced through stereo subwoofers if you demand the most accurate reproduction.
Putting the math aside, the best way to demonstrate this is to swap between one and two subwoofers with a real stereo recording, and it will be obvious."
https://www.kenrockwell.com/audio/stereo-subwoofers.htm