Sheba, welcome. Just speaking generally, the M50s are fine speakers which your 1014 would be more than adequate to drive, and you'd almost certainly be very happy with them. If you mean surround speakers that actually would be mounted in the ceiling, unless there's some reason that it has to be that way you'd be able to get better sound with speakers(e.g. QS4s) mounted high on(but not in)the side walls. The lack of a wall immediately behind wouldn't be a problem.

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Enjoy the music, not the equipment.