That will depend on which SongCenter you have--the one with the dome tweeter or the ribbon. If you have the ribbon, it's postioned to operate with the speaker mounted horizontally. You can't place the speaker vertically unless you rotate the tweeter, and I don't think that can be done easily. If you have the dome, then you will get the broadest and most even horizontal dispersion with the cabinet mounted vertically. Not many people have the room to do that, so it's usually academic. If you can mount the center vertically, then you will probably get the best sound stage that way.
