Carl St. Clair conducted the Pacific Symphony in a milestone concert for the Santa Ana ñ based ensemble Wednesday at the Orange County Performing Arts Center in Costa Mesa, with the orchestra playing with a depth, resonance and transparency that put it into a new league altogether.

The concert didn't start out so auspiciously, however, but some of that had to do with the music, Gordon Getty's Three Waltzes. Getty, who was on hand to take bows, doesnít seem to trust his own lyrical instincts or creativity. He comes up with ideas and gestures that have attractive profiles, but two bars later, he either repeats himself or goes on to something else. The music starts and stops and loses any flow.

The next problem was more complicated. Next to Eduardus Halim's extraordinary pianism, evidenced in a poetic, fiery account of Chopin's F - minor Concerto, perhaps any orchestra would sound somewhat coarse and crude. The Pacific certainly did.

The last student of Horowitz, Halim is an aristocrat of shading and dynamic, his spidery dexterity eliciting a multitude of colors and ideas. One doesn't always agree with them, but he sounds like an individual in this music and that is rare.

But after the intermission, with Beethoven's "Eroica" Symphony, it was a whole new sonic ballgame. The orchestra was beautifully balanced and rich in detail. The playing had texture.

Perhaps some of the improvement was due to the farther-forward position of the strings, which had been pushed back to make room for Halim's piano in the first half. But then, too, St. Clair's conducting has become cleaner and more purposeful. He addresses the whole orchestra now, not just the top of it. He shapes phrases and pays attention to the composer's markings. He doesn't let lines die at the end. He gets across the complexity of Beethoven's ideas.

The presence of Kevin Connolly, the new concertmaster, also appears to be paying dividends, with his detailed phrasing mirrored throughout the violin section. Even better, the principal string players are performing like a responsive quartet, and that unity is mirrored in their sections as well.

There was a freshness and zest to the performance unmarred by technical weaknesses or inadequacies. There have been deeper and more profound performances of the work, but this one lifted the Pacific out of a regional rut.