Theoretically exact placement to the millimeter is necessary, but that would require your head to be locked into place with the same precision. Take these requirements with a grain of salt.
Clear your mind by having someone help you do a blind test. Set up your current speakers precisely. Listen. Have your helper move, or not move, the speakers without your knowledge, eyes closed. Listen again, repeat as many times as needed to determine whether you can reliably hear a change. You might be surprised.
Clear your mind by having someone help you do a blind test. Set up your current speakers precisely. Listen. Have your helper move, or not move, the speakers without your knowledge, eyes closed. Listen again, repeat as many times as needed to determine whether you can reliably hear a change. You might be surprised.