"Sound Reproduction" by Floyd E Toole on Amazon for $23 in paperback. It will be the best $23 you ever spend. It should be mandatory reading for all audiophiles, especially those who are dealing with speaker set up. Too much of the stuff you will read here is either uninformed or presented to stimulate commerce.
@newbee , +1, I think a lot of it leans towards "commerce stimulation", i.e., the dealers and the appointed pied pipers for certain product and so on ( I doubt some of these guys are all that genuinely uninformed).