Written only four years apart and even sharing the same key of D minor, the Voces Intimae Quartet of Jean Sibelius and the First Quartet of Arnold Schoenberg make for uncommon yet highly suitable disc-mates. The early Schoenberg quartet is still very much a tonal work while hinting at some of the techniques and methods that would come to be inextricably identified with the composer. Both works are passionate yet restrained, sophisticated yet accessible. Performing these two breathtaking quartets is the Tetzlaff Quartet, an ensemble that actually had its beginnings playing Schoenberg's Op. 7. Like the subtitle for Sibelius' quartet, the Tetzlaff Quartet excels at producing a profound, breathtaking intimate sound quality. Both Sibelius' central Adagio movement and the hushed, still conclusion of the Schoenberg Finale are treated with sublime delicacy and careful control over dynamics and vibrato. That being said, the Tetzlaff Quartet is just as comfortable, producing a robust, vibrant sound. Refined technical abilities -- including precisely matched intonation, articulation, and phrasing -- allow such equally cultivated musical skills to become the listener's focus. Nothing is rushed, instead savoring each sweeping phrase in the Sibelius, and each small, nuclear motive in the Schoenberg. Though these quartets are infrequently performed, the Tetzlaff quickly proves to its audience that it is equally deserving of admiration and gives listeners a noteworthy recorded example.