Conductor/pianist Daniel Barenboim is well-known for his sometimes controversial efforts to bring Israelis and Arabs together under the banner of art. In the wake of the ongoing violence in Northern Israel and Southern Lebanon, Barenboim’s “Peace Orchestra” is experiencing the same tensions and anger that are exploding across the region. But according to those in the ensemble, whatever tensions exist can always be channeled into the performance, and some observers even say that the orchestra sounds better than it ever has as a result of the emotionally charged backdrop of current events.