LA JOLLA — In 18th-century France, groups of men and women would gather in private homes for events known as “salons” — evenings of music, poetry and cultural exchange presented for mutual enlightenment. Today, that tradition carries on in San Diego, where a handful of North County chamber music-lovers are regularly opening their living rooms for private house concerts. Among these modern-day salon hosts are Marty and Sherry Bloom of La Jolla. For the past 12 years, they’ve invited fellow music-lovers into their living room for food, fellowship and first-rate chamber music. Mart...