I understand that speaker response will vary depending on proximity to room boundaries such as floors and walls.

For a given distance of a driver to a boundary at a given frequency, how do I calculate the amount of reinforcement? Is the driver to boundary distance measured from the center of the driver or from its closest edge?

Also, I've read that boundary reinforcement is 6db of sound pressure vs. 3db of sound power. What is the difference? Which would you expect corresponds to the db-calibrated volume control my preamp?

Thanks!

- Ken