The Boston Symphony Orchestra has its new music director and conductor, number 15 in its storied history. It’s Andris Nelsons, who begins his tenure by inviting two close associates, soprano Kristine Opolais and tenor Jonas Kaufmann, who help him perform some of his favorite works, starting with the piece that made Nelsons, at age 5, want to pursue music: Wagner’s Tannhauser Overture. For a full review, see Tom Brinkmoeller’s Raised on MTM. Check local listings.