Eric, another welcome. Since you're going to have room beneath the projection screen, yes you should definitely consider using a vertical M22 center there, which would match up very well with M60 mains(as would a third M60, of course). The only problem that sometimes occurs with using a relatively large vertical center similar or identical to the mains is having the room to place it, but with a projection screen that problem doesn't exist.

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Enjoy the music, not the equipment.