If you've never heard a recording of Willem Mengelberg conducting the Concertgebouw Orchestra Amsterdam, there's nothing you can do to prepare yourself. The tempo manipulations and dynamic modifications of Bernstein and Mitropoulos are nothing compared with the radical changes Mengelberg puts music through. As demonstrated by this 1941 recording of Tchaikovsky's Pathétique, Mengelberg slows down precipitously for second themes, pushes forward relentlessly for developments, stops time abruptly at climaxes, and adds portamento to every possible string line. And that's nothing compared with his 1938-1942 (there was a war going on) recording of Bach's St. Matthew Passion. Naturally, Mengelberg not only performed the work on modern symphonic instruments including harp and employs operatic soloists, two huge mixed choruses, and children's chorus -- he was, after all, born and raised with the late Romantic attitude toward Baroque music -- but he also added voluptuous colors, fuliginous textures, lugubrious tempos, and tenebrous expressivity to Bach's austere music.
But, it works. Mengelberg's Pathétique is an affecting personal tragedy, and his Passion is a moving universal tragedy that should persuade those with open ears and hearts. Opus Kura's restored sound is of the "bring back as much of the music as you can and let the clicks fall where they may" school, and although this approach may, like Mengelberg's conducting, be literally disquieting to some listeners, it nevertheless works.