Agreed, if more than one listening seat is involved.It has nothing to do with seats and everything to do with mono (one sub) having zero chance of reproducing inter-aural spatial effects/lateralisation etc, as has been covered many times here, including many AES links by your truly. Einstein rules of insanity applies.By what metric(s)?All. Nearfield = zero modal problems at seat. Nothing to "correct" (and/or "incorrect" elsewhere).
Only issue might be phase due to propagation delay vs the mains, but the lower you cross, the less that matters as the low pass filter of the sub will automatically introduce a delay...and it will all appear in the frequency domain at given crossover, so easily measured (though not necessarily heard, depending on Q of any notch).
Please read, there are links to over 40 studies compiled https://secure.aes.org/forum/pubs/conferences/?elib=17270
We can consider two questions: whether one sub in a system is better than none, or whether multiple subs are better than one. An auxiliary issue would be, are the main speakers 'full range' or not?
The 2006 Wilson/Meridian review that you cite considers the literature of multiple subwoofers versus one (and to a degree, full range mains versus limited mains). It doesn't really consider none vs one, which was something I addressed above. The OP thinks 1 sub in a stereo setup is 'sounds wrong' but I would say it's likely better than no sub, given that it offers more flexibility in locating the LF source (that said, the OP's personal situation appears to preclude most locations, and it could be that his limited placement options 'sound wrong', but many factors could be in play ) . I don't question that multiple are likely to be better than one, assuming flexibility in placement.
The paper reviewed what we knew in 2006 about how to provide uniform bass across a listening area (i.e., taming modal issues) and how to provide low-frequency spatial information ('stereo bass' -- i.e, a system where subs are receiving different signals). I don't see in it a recommendation for nearfield subwoofer placement. It does favor multiple subs for addressing both issue -- at least two to allow 'presentation of spatial information' . If anything , the review appears to find the most promise in a system with 5 full-range loudspeakers + DSP.
It is however unclear to me from that review whether 'stereo bass' matters in typical-sized consumer rooms. It's not something that gets cited a lot as a 'must have', even now 12 years later. (For decades during the analog era, bass was 'summed to mono' in commercial releases anyway. ) If it *is* a goal, then we need at least two LF sources and they need to have some left-right side-to-side separation. I certainly don't dispute that. But I'm honestly not sure I have ever really experienced 'stereo bass' in a home setup. I'm curious to do so.
I haven't read all the cited references, except for the Welti/Harman-originated ones I'm familiar with from years ago.