It may sound like hyperbole, but I can divide my professional career pretty clearly by the time before I read this book and the time after. Before reading McCarthy's book I was using professional sound systems mainly by assumption, guessing, and what I had seen other people do. I was setting up stereo systems at every venue, measuring their performance with a stupid hand-held RTA, and optimizing with a single graphic EQ. Learning about how to apply the physics of sound to my work as an audio engineer changed my life. I don't always do the right thing now, but at least I have a better idea of what I'm doing.