There are only two ingredients needed to make a José González performance a complete experience: his hoarse yet delicate voice and his emotive guitar playing. When the Argentine-Swedish singer-songwriter pairs up with String Theory, a collective that, among other activities, also functions as an experimental chamber orchestra, it adds layers upon layers to his music. In 2018, the two entities toured Europe, the results of which were released last month as a live album. That unique, enhanced presentation of selections from three of González’s better-known solo albums now comes to North America. The String Theory bring a touch of folk, a touch of musical theater and a touch of the esoteric to González’s compositions, whose spare but immersive nature lends itself nicely to String Theory’s creativity, particularly on favorites such as “Leaf Off/The Cave” and “Down the Line.” Also on Sunday, April 7.