An Orange County Superior Court judge has ordered officials of the Pacific Amphitheater in Costa Mesa to reduce sound levels during rock concerts at the 18,700-seat facility. Although the restraining order is not definite about what penalties might be assessed, amphitheater officials, rock bands and their management are troubled by the action. "We're dealing with something that is a criminal matter--potentially. People could go to jail," Deborah Nesset, attorney for Ned West, Inc., which owns and operates the Pacific, said Friday. Alex Hodges of ICM Talent, one of the largest booking agencies representing dozens of rock acts including Def Leppard, Motley Crue and Ozzy Osbourne, has said the agency's clients would not perform at the Pacific if they were forced to turn the volume down.