Center Speaker. YES, centered right under the monitor! If you do not change a 5.1 program to forced 2.0 or forced 2.1, then all the specific center content will be MISSING.
Always use Center Speaker: NO
I often force a streamed source to 2.0 and it often sounds better, some pseudo processing may have been done along the way.
When the original 5.1 is done well, it is terrific!
Dual Mono Phantom Center at least captures the content, but just like any Stereo Imaging, there is an entire front, and the mix/positioning can be anywhere the director want’s it, that imaging will be compromised when processing the center content to dual mono.
This little Bose Center Channel can do a darn good job.
Bose VCS-10 Little Center Speaker
Initially I used it behind a Big CRT in a big cabinet, another time behind the open legs of a 47" Monitor, and lastly under the riser below my 55" monitor I showed above. In all cases, the sound appears to come from the Image, and the content’s imaging was created.
I switched to the Klipsch R-34C, no rear vent
It is very cool looking, but I didn’t compare, so better than the Little Bose? The Bose has some output from vents on it’s top, they were below but under by the riser’s glass shelf. Klipsch is super efficient, I had to cut my center signal’s strength in the AVR to blend with the DBX Soundfield 100 fronts.