Soundbar in the Center
What do you think of this approach? Paradigm makes a 3-channel soundbar, the Millenia 20 Trio (shown above). I like my Paradigm speakers, but I thought that looking at other brands might be a good thing to do.
I see a couple of problems with this approach. First, I assume that two of your in-walls are in the front of the room flanking the screen, which means they will not work as surround speakers. Second, using a 3-channel soundbar for the front LCR (left, center, right) is not ideal because the left and right channels are not separated by enough distance to create a wide soundstage. (Such a soundbar works far better than any TV's internal speakers, but it's not as good as fully separate speakers.)
In your case, I would get a center-channel speaker that most closely matches the tonal characteristics of the in-walls. Such a speaker will undoubtedly come from Paradigmit's rarely if ever a good idea to mix different brands of speakers, because their tonal quality will probably not match well. This tonal matching is critical for good home-theater sound so that when a sound pans from one channel to the next, its character doesn't change.
You don't specify the exact model of in-walls you have, but I would get the Paradigm center-channel speaker that most closely matches them in tonal quality. This often means that the center has a similar compliment of drivers, but I would contact Paradigm for its best recommendation. If your current center speaker is a Paradigm, you might already have the best match for the in-walls.
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