spenav OP, others
Don’t Skip a Center Speaker, even if it has to be small, or behind something, try one
I love music videos, concerts ....., streaming performances, i.e. search YouTube, Voice, it is all over the world, and there is quite a lot in English from all the foreign countries to enjoy
I often force 2 channel and get better results when pseudo surround has been created somewhere along the line
I am surprised that you do not have a true center channel, when content is originally created, center dialog/content does not exist in FL and FR so Phantom Center cannot create what doesn’t exist. There is no need for Bass in the center.
I have found a true dedicated center, even small, the location just below, or even behind the image if the sound can get thru legs or an open base, in my current setup I built a riser to give me a 7" high space for a center speaker. (We made temporary spacers below to test the image height/neck comfort and see any reflections while sitting/viewing, didn't want to go too high).
here is a very efficient Klipsch Center (no rear ports) (that’s art, not a speaker above the tv)

I just changed to a smaller Jamo Center that blends better, the Klipsch is too efficient, the Jamo is real Cherry and blends with my DBX Soundfield 100’s better

my 1st center was a very small Bose VCS-10, it sounded very good, even once from behind a big CRT in a wall unit (notice the top slots)