Loudspeaker setup is a funny thing. Inches matter for the speaker's position, yet those minuscule changes affect a much larger area in the seating position. Why would that be?
With a well-designed loudspeaker pair with flat off-axis response, the sweet spot for listening is rather broad. For example, Music Room Three with the aspen FR30s has a full three-seat-wide area. And, in any one of those seats, you can clearly hear small incremental differences in speaker positioning.
There are a couple of things going on here. First, think of the speakers as you might a flashlight pointing at your listening position. The farther you are from the source of light, the more spread you get from the beam. Small incremental changes at the source change brightness levels in a broad area at the listening position. Secondly, we cannot think about speaker positioning as affecting only the focus on the listening position. We are also impacting the speaker/room interaction.
Combine the impacts of audio "spread" and room interaction, and it should be a bit more obvious why inches matter.
