I have a problem with the center speaker, since the stud goes directly down through the middle of the wall. So my options are either mount it vertically to the left or right of the stud (slightly off centered). Or look into getting a section of the stud removed (I have access to behind the wall), then putting it in horizontally, on center.
Do you think that speaker would be alright mounted vertically? Would it be a big deal being slightly off centered? I plan on painting them to blend with the wall, so hopefully it wouldn't look too visually unappealing.