Kevin, welcome. Yes, the ideal is to have identical speakers across the front, and this also includes an identical vertical orientation. You haven't described why you wouldn't have room under the screen, since this is usually an ideal situation for a vertical center the same as, or at least as close as possible to, the mains. If it would be possible also consider using an M60 or even an M22 there.

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Enjoy the music, not the equipment.