Nowhere is the relationship between classical music and folk music as incestuous as it is in Hungary. Between 1905 and 1940, Hungarian composer Bela Bartok made field trips throughout Central Europe to collect thousands of authentic peasant melodies, many of which he adapted for his Beethoven-inspired string quartets, Brahms-inspired concertos and Bach-inspired sonatas. When the Western World's folk revival came to Hungary in the '70s, the young musicians in Muzsikas made similar field trips and found many of the same melodies, but they were more interested in re-creating the original folk arrangements.

These different approaches to the same source material are explored in fascinating detail on the new Muzsikas release, "The Bartok Album." A typical sequence begins with Muzsikas playing the Romanian dances of Hungary's Torontal region in the local style. This is followed by Bartok's actual 1912 wax-cylinder field recording of a Torontal fiddle tune. Then Muzsikas fiddler Mihaly Siphos joins classical violinist Alexander Balanescu for a version of Bartok's Violin Duo, No. 44, which is based on the same melody. Finally Muzsikas plays a Transylvanian dance that uses the same melody in a different folk context.

Thus we hear the same folk melody as it sounded 87 years ago, as it sounds in a classical setting and as it sounds in the hands of Hungary's finest active folk troupe. Many other melodies get a similar treatment on this 22-track album, which features four vocals by Marta Sebestyen, the world-music star and frequent Muzsikas collaborator. From any angle, these are inexhaustible themes handled by superb musicians.

Appearing Thursday at the Birchmere. To hear a free Sound Bite from Muzsikas, call Post-Haste at 202/334-9000 and press 8110. (Prince William residents, call 690-4110.)