Placing the speakers in the proper position in the room might be the single most important thing you can do to improve sound quality, create a 3-dimensional soundstage, and get that perfect center image. The “image” is the illusion of sounds coming from defined points in 3D space based on the recorded material, completely separate from the speakers. The “soundstage” refers to the ability of the speakers to project the sound beyond the boundaries of the speaker, and create a sense of depth, scale, and realism. For many people, not every part of the ideal setup is possible, due to limitations of their room. This is okay. Do as much as you can, and then sit back and enjoy the music, purely understanding that following the tips below will enhance the sound and improve the experience.
A good starting point for setting up a pair of speakers is to have them in an equilateral triangle.
The triangle is created as one line directly between the speakers, and one line from each of the speakers; the left towards your left ear, and the right towards your right ear. As such, the distance between the listener should be equivalent to the distance between the speakers. The second important part of placement is with regards to the distance between the speakers and the boundaries of the room. Ideally, the speakers are pulled away from the front wall (the wall you look at if you are looking at the speakers head-on) and equidistant from the side walls, preferably more than 2 feet away. As the speaker gets closer to the walls, bass energy and other reflections will build-up, which distorts the sound coming from the speakers. A good rule of thumb with regards to distance from the front wall is to have the speakers pulled a third of the way into the room, with the listener 2/3 into the room from the front wall.
The last piece of the equilateral triangle is the angle of the speakers, also known as toe-in (see image). A toe-in of zero would mean a line is pointing straight ahead from the center of the speaker driver, and your speakers are facing directly towards the rear wall. Adjust the toe-in and see how it affects the sound. Usually, a larger toe-in will increase the definition of the center image but narrow the soundstage. Decreasing toe-in will do the opposite. There is a “sweet spot” where you get the best of both worlds, and usually this is when the line coming out from the speaker aligns with your ear on that side from your listening position. With this logic, a listener seated closer to the speakers may require more toe-in to get a good center image than someone who is sitting farther away. I have found it is best to start with no toe-in, and then slowly rotate the speakers inward. It is easy to overdo it with toe-in, which can lead to a lack of clarity and separation in the different parts of the track.
When adjusting toe-in on the speakers, make sure the toe- in is the same on the left and the right speaker. You can do this by keeping the front outside corner of the speaker in the same location, while moving the front inside corner of the speaker. Measure the perpendicular distance from the front inside corner down to the front outside corner. I have found that a mismatch in speaker toe-in of only one inch can substantially affect the sound, so make sure to accurately match the two speakers as you adjust the toe-in of both. The last part of speaker setup is making sure that the tweeter is at the same height as your ears. This will lead to the most clarity and the least perceived roll-off of the sound. If you can, make sure what you sit on to listen puts your ears level with the tweeter (the part of the speaker responsible for recreating the high frequencies). You can also buy speaker stands at different heights, which you can tailor to the height of your ears at your listening position.