Lost in the debate about contemporary music's viability is the point that new pieces must be performed well. Countless new works are lost on audiences because the players or, as it was yesterday at Heinz Hall, the conductor does a poor job of presenting them.

	Guest conductor Mark Wigglesworth better handled Schubert's Symphony No. 9 with the PSO. Click photo for larger image. Pittsburgh Symphony Featuring: Mark Wigglesworth, conductor; Leila Josefowicz, violin. Where: Heinz Hall, Downtown. When: 8 p.m. today and tomorrow. Tickets: $17-$69; 412-392-4900.

Leading the Pittsburgh Symphony Orchestra in a program that included works by contemporary composer John Adams, debuting guest director Mark Wigglesworth tended to conduct against the grain, obfuscating internal structure.

Adams' energetic "Short Ride in a Fast Machine" got the concert revved up, as it always does. Wigglesworth kept the texture clear but did not elucidate its infrastructure. While this is a short piece, it is not a straight fanfare, and such things as the tuba entrance midway through lacked emphasis.

Wigglesworth struggled more with Adams' Violin Concerto, which, completed in 1993, is now a staple of the orchestral repertoire, even if this is the first time the PSO has performed it. The three-movement concerto operates through a complicated overlay of rhythmic lines, sophisticatedly evolved from the days of minimalism. Adams has explained he wanted to "confound" the simple pulsation of minimalism, and music in general. The violinist, in this case the talented Leila Josefowicz, interacts in marvelous ways, from soaring above it to grooving in the trenches with it.

But Wigglesworth inexplicably pushed this underlying framework down, turning the interaction of rhythms into a quiet muddle. While this allowed Josefowicz to be heard, the notes she plays mean more when complemented by the harmonic and rhythmic context. He also failed to shepherd the crucial accelerandi of the first movement. The second movement employs a ground base upon which Adams creates lines that fade in and out ephemerally with a bittersweet tinge of nostalgia. But again, Wigglesworth subdued the repeating bass figure and used a sluggish tempo, compromising the piece's effectiveness and drive.

It was disappointing enough to know that most people who heard the performance will think the Violin Concerto is long-winded because it seemed that way under his baton. However, the performance also squandered the fine effort of the guest soloist, Josefowicz. She played with a beauty of tone rather uncommon for the contemporary scene. This piece makes the violinist work, but she made it seem a joy. Even the perpetual motion of the frenetic finale had a delightful freshness to it, giving a bouncy rondo feel to the movement.

The second half opened with Wigglesworth conducting Schubert's Symphony No. 9. He obviously knows this piece better than the Adams works. He conducted without a score and with a firm command of the work. The conductor desired balance and clarity, which is admirable, but he often achieved it by subduing sections, such as the violins, rather than enhancing others. This method left the work enfeebled at points.

It was marvelous to hear the repeat of the exposition of the first movement, something too often dispensed with by conductors. His approach of quieting the strings did allow for some captivating wind performances to emerge, including the trombone section and oboist Cynthia Koledo DeAlmeida. The flute section included guest Demarre McGill, one of two finalists for the principal flute position.