This set of Sibelius' early piano quartets is clearly marketed to completists, and it will reward them for their interest. The first work on the program, a four-movement Quartet for two violins, cello, and piano from the composer's nineteenth year, sounds like an elegantly accomplished pastiche of Mendelssohn's Piano Trio in D minor. The second work, a five-movement work for violin, cello, and piano four hands, is called an opera and, although entirely lacking in vocals, it does have an amusingly melodramatic tone. The Scherzo for violin, cello, and piano four hands sounds like a roughened Schubert. The Andante cantabile for piano and harmonium is sweet parlor music. The Quartet in G minor for violin, cello, piano, and harmonium sounds like Schumann in an especially light mood. The closing Quartet in C minor for two violins, cello, and piano from the composer's 26th year is the latest work on the program, but it still sounds less like Sibelius than Nordic-inflected Beethoven. In other words, this is a great window into the composer's early leanings and influences, and a bridge between his mature style and nineteenth century. The performances led by pianist Folke Grasbeck are uniformly persuasive and BIS' sound is admirably realistic.