S9, since you're on a tight budget, let me suggest that you consider using a third M2 vertically as the center speaker rather than a VP100(or any horizontal MTM design).As far as the receiver, if the XR-50 still has a 100Hz crossover, something slightly lower would be a bit better, but 100Hz should give acceptable results. The Hsu can handle that frequency with its own internal crossover switched out.

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Enjoy the music, not the equipment.