Welcome. If I followed, you presently have no sub and only the small Sonys for side surrounds. Also, you can get the QS4s and EP175 for less than what new QS8s would cost you. If this is the case, my view would be that although the QS8s are better, the combination of adding the EP175 and QS4 side surrounds for less money would add more to your listening enjoyment, so buy now.

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Enjoy the music, not the equipment.