Lacking the range of dynamics of the string quartet and the regal, extroverted sound of the brass quartet, the traditional woodwind quintet has its special if at times underrated musical virtues. The Aspen Quintet, a class act in contemporary ensemble playing, spirited these virtues to the Library of Congress' Coolidge Auditorium Saturday night. The musicians' level of performance was not consistent -- it took them until late in the program to deliver their very best -- but when they were good, they were superb.

The group offered a somewhat eccentric mix of works, consisting of Paul Taffanel's "Quintet for Woodwinds," written in 1880, Hans Abrahamsen's 1978 "Walden" (or "Quintet" No. 2), Villa-Lobos' "Quintette en forme de Cho ros," Frank Zappa's 1985 "Excerpts from Times Beach" and Rameau's "Suite in G."

The Taffanel is an overwhelmingly derivative work that sounds less like itself and more like Schumann than Schumann and more Brahmsy than Brahms. Consequently such a work needs in performance a special dose of fresh interpretation and imagination. In this case, it served as the concert hall's acoustical test balloon, for the ensemble let go with some sloppy horn and bassoon playing and some reedy, vibrating sounds at the high points of several crescendi in the first movement.

The group's technique became more disciplined in the Abrahamsen, but this work is so pretentiously minimalist and antiphonal that the sounds on stage probably distracted the audience from any vestige of music in the air. In the face of so many conspicuously scored rests (actual extended silences where all five musicians counted measures but played not a note), the audience knew the piece was over only when the clarinetist adjusted his reed and the French horn player emptied her spit valve. (Mandatory and confused applause at this point.)

But the Aspen Quintet began exhibiting unsurpassable virtuosity in the Villa-Lobos when the music began sounding more like music. This work was spiced with syncopated and intricate rhythms, ingenious combinations of the different five instruments, and a tempestuous French horn solo in counterpoint against a plaintiff oboe melody.

And then came a surprise. The group continued its level of excellence in a specially commissioned work composed by rock star Zappa. The Zappa work, though minimalist and antiphonal like the Abrahamsen work, did not suffer from Abrahamsen's shortcomings. Zappa seems to know how to work his rock charm into the idiom of classical music. Perhaps the audience witnessed the beginnings of some special merger. The Aspen Quintet ended the evening with a mesmerizing rendition of the Rameau.