After their recent forays into the modern and contemporary repertory, Pentatone’s “Golden Age” indulges instead in an irresistible nostalgia for Met-proven voices: unpretentious yet charmingly picturesque, the album evokes the hedonistic atmosphere of days sadly gone by—when operatic luminaries (think Tucker, or Roberta Peters on the “Ed Sullivan Show”) dazzled with sheer vocal prowess. Show business at its best, then—or {…}