I had a trip lately where we rode this fancy bus with speakers on both sides of the overhead carriage. What I noticed was that the speakers were facing each other. Will there be a negative effect on the speakers with this kind of setup?
I don't think there is a problem with that setup because there is still a space between the speakers. There will be a problem when we positioned the speakers towards each other within a close proximity that they will double the vibration that each speaker will produce. This is how I understand it so maybe some can enlighten us on this.