Classical music is supposed to be immune to the kind of format requirements that constrain mainstream radio and television. And yet modern masterworks by great composers go unplayed: They're too short to be worth the effort of assemblage or their instrumentation is odd. Proof came from Orchestra 2001's concert Sunday at Swarthmore College, full of undeservedly neglected music.

In fact, a full 15 minutes of stage reshuffling was necessary between Richard Wernick's Kaddish-Requiem and Henri Dutilleux's Les Citations, so different were their sound worlds. (Orchestra 2001 simply showed a documentary film about one of its visits to Russia.)

Rewards for the wait were considerable. Oboe, bass, harpsichord, and percussion is the unlikely lineup for Les Citations, a work full of ruminating solos for oboist Richard Woodhams, bass writing that borders on jazz, and references to 16th-century composer Clément Janequin that show how new and extremely old music share the same alluring strangeness.

The performance under James Freeman was unusually explosive (gongs are involved) - to be expected when following Wernick's Vietnam War-era piece venting the composer's outrage. The piece seems not to have the dimensions typical of Wernick, yet the message remains compelling, drawing from a taped recording of the Kaddish sung with elemental power by Cantor Ramon Gilbert.

The short, exotic, 1951 Le Merle Noir by Olivier Messiaen prepared one's ears for the concert's best surprise, Joseph Schwantner's Music of Amber. When the piece was written in 1981, the neo-tonal movement was more controversial and awareness of gamelan music (one key to this piece's riches) wasn't so widespread.

Now the seven-member chamber ensemble dominated by piano and percussion feels marvelously current, with gamelan-like ostinatos full of melodic interest while their repetition delivers gentle momentum. The astonishing conclusion's aggressive percussion is intensified by contrapuntal cross rhythms, ending with a quiet, eerie, sleight of hand.

The performances felt more than assured. Flutist Mimi Stillman, mezzo-soprano Freda Herseth, and pianists Marcantonio Barone and Charles Abramovic were particular models of clarity, rendering the thoughts behind the notes inescapable.