This actually comes up a lot, I would not lay down your m22's as they are designed to be vertical speakers with a good horizontal dispersion of the sound. If you lay them down, your horizontal dispersion just tuned into vertical dispersion. The 150 is a center channel speaker and should do fine. The best center is a matching speaker of your left/right, if that is m22's, then a standing m22 would work, but don't count out the 150.
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