Based on the Sophocles tragedy, Richard Strauss’s Elektra of 1909 represents the first of his several collaborations with librettist Hugo von Hofmannsthal, who in this instance had already written an eponymous play. It is the second of Strauss’s two highly modernist operas, and deploys dissonance, chromaticism and extremely fluid tonality to an even greater degree than his first, Salome.  The opera is expressionistic in every sense since the adaptation of the...