Recorded in performance, but one act at a time so that the principals could sing full-out, this is one of the most electrifying opera recordings of the stereo era. Birgit Nilsson blazes as Isolde, and Wolfgang Windgassen's Act-III evocation of the delusional Tristan is heart-wrenching. Karl B"hm inspires transcendent playing from the Bayreuth forces, and the sound is stunning. --Ted Libbey