As Neeme Jarvi prepares to leave the Detroit Symphony after 15 years, he has already taken up his next challenge as music director of the embattled New Jersey Symphony. Most observers would consider the NJSO a significant step down from Detroit’s higher-profile orchestra, but for Jarvi, Newark offers a chance to wind down his career with an enthusiastic group of musicians who don’t mind taking a few chances in the programming department, and to do so without all the inherent pressure of a world-famous ensemble. Oh, and he gets to live in Manhattan, and see his grandchildren nearly every day.