Without proper alignment processing, you can not employ more than one loudspeaker in the same acoustic space.
I’ll go further to say that without proper alignment processing, there shouldn’t be more than one round or square thing in any given speaker box itself. Ten feet, four feet, or two inches apart, any proximity of speakers can cause serious articulation problems. This stuff was proven hundreds of years ago, and it’s roughly why one’s ears are on opposite sides of one’s head.
Today, we have the time-domain technology to conquer phase problems. If you don’t, or if anyone tells you different, please just call me. I’ll clone myself and speak simultaneously at a distance of one foot and two feet from your ear. Alternatively, just check out this post.