Audio industry pioneer Dan D’Agostino built a cult-like audiophile following when he co-founded the high-end audio company Krell in the early ’80s. He says after investors forced him and his family out of the company in 2009, he plotted his comeback in Cave Creek with Dan D’Agostino Master Audio Systems, which specializes in small and mighty (expensive) amplifiers. “We thought we could bring some sound quality to the market that wasn’t there,” says company president...