Esperanza Spalding is certainly not shy of ambition. The singer, bassist and composer lit up the jazz world with 2008's "Esperanza," and where she could have offered more of the same this time out she's instead raised the proverbial bar on "Chamber Music Society," creating her own chamber approach by incorporating string players and taking on a challenging repertoire that shows a new level of sophistication as performer and -- in collaboration with co-producer Gil Goldstein -- arranger. Kicking things off with a musical adaptation of the William Blake poem "Little Fly," rendered by Spalding and her bass and the string duo, serves notice that she's focused on new vistas here. She also teams with Brazilian vocalist Milton Nascimento on her own "Apple Blossom," takes an aggressive vocal course on the Dimitri Tiomkin/Ned Washington piece "Wild is the Wind," puts a classical tone on Antonio Carlos Jobim's "Inutil Paisagem" and scats like crazy on tracks such as "Really Very Small," "Chacarera" and "What a Friend." Despite the changeup, this is one Society that should not have any problem-recruiting members.