Earlier this year, as that unmistakable bass line of the Pretenders’ My City Was Gone faded into the background, Rush Limbaugh opened his daily three-hour broadcast with characteristic bombast. “[According to the] latest research data,” he intoned, “the audience is expanding at near geometric proportions, as people seek guidance, answers, explanations, information, and an answer to the basic question, ‘What the hell is happening out there?’" ... And yet, there are signs that all is not well in the Limbaugh radio empire. Because even as his influence is sky high and his dominance at the top of talk radio remains...