Obviously, because every room, speaker and component setup is a different, there is no way to create a “one size fits all” solution. In fact, finding the ideal speaker placement is pretty much a trial and error process. Fortunately, there are a few basics to make the process a bit simpler.
To maximize the soundstage and provide the most dimensional sound, the left and right speakers must be placed symmetrically to one another. The two speakers should be, at minimum, as far apart as the distance from each one to the listener; typically six feet or more.
Think of yourself and your left and right speakers as points of an equilateral triangle; as you start your experimentation, this triangulation gives you the best baseline. Keep the path from speakers to listener unobstructed and, for best high-end response, the tweeters should be at ear height and aimed to the primary listening position.
Larger rooms generally offer better bass response. Bare walls and uncarpeted floors, particularly in a room that is virtually square, can cause excessive echo. Absorptive materials, such as area rugs, wall hangings, etc. can reduce reflected sound dramatically. If the speaker is bass ported, the positioning is more critical. Rear-ported speakers should be placed somewhat away from walls.
As with any type of experiment, you’ll need to keep track of the changes you make as you move your speakers; note what you like or dislike before you move on to the next speaker position. And, make your changes in small increments, so that you have a consistent baseline from which to assess the differences in sound. Again, this is a subjective process, so the bottom line is: trust your ears!