Is it pure individualism or a point of honor that keeps Philadelphia composers from sounding even remotely alike?

That question was just as easily asked over the weekend as 30 years ago, when modernists ruled. Now, Andrea Clearfield juggles traditional lyricism and genial polytonal collages with a virtuosity that never contradicted the title of her new piece, Romanza, premiered over the weekend by violinist Gloria Justen and Orchestra 2001. It could be a lasting contribution to chamber concerto repertoire: How many composers so coherently morph from a string quartet to Stravinskian neoclassicism?

Only miles away on Saturday (but light-years apart), the American Composers Orchestra played five works by area composers at the Annenberg Center, with Princeton-based Alan Tormey weaving webs of sound suggesting Renaissance polyphony splintered mercilessly and reassembled with a funky beat. The title: Cleveland Is a State of Mind.

Such well-delineated contrasts, though, are provisional. At Orchestra 2001's concert, two composers once considered to be at opposite poles turned out to have important things in common. Avant-gardist emeritus George Crumb was represented by his 1976 Dream Sequences (Images II) showing his unique sound shapes at their most hypnotic. Joseph Schwantner, a throwback to traditional tonality, seems more durable than ever before in his 1979 Sparrows, thanks to musical imagery created from precise, unsentimental sonorities that smack of Crumb's photo-realist clarity.

At the 2001 concert, Crumb and the more rigorous, modernistic György Ligeti (in his Chamber Concerto) were heard in pieces built around central masses of sound. Crumb's glass harmonica created a single, vibratoless unwavering chord; Ligeti's progressed from one drone to another with underlying rustling created by his trademark micropolyphony. The program notes compared Crumb's drone effect to cicadas; that better applies to Ligeti.

You had to be so proud that Orchestra 2001 navigated these composers so much on their own terms (particularly if you had navigated Sunday's nor'easter to Swarthmore's Lang Concert Hall). Good Crumb is expected. But James Freeman conducted Ligeti with a feeling for the alternative logic that made quirky movement endings feel conclusive. All that, plus modern-music soprano Lucy Shelton: Schwantner wrote Sparrows with vocal lines built around the kind of intervals she negotiates seamlessly, even when not at her best.

The American Composers Orchestra concert showed area composers decisively staking out stylistic territories. In Gaeng, Settlement Music School teacher Michael Djupstrom drew upon Laotian music he heard among immigrants in his native Minnesota. The glistening sonic soup in the remarkable Finishing by Princeton-based Greg Spears used drone effects less prominently than Crumb, but using dictaphones. You could mistake Scirocco Dances by Wilmington-born John B. Hedges for a mercurial melange of simultaneous events; on closer inspection, they have secret, conspiratorial relationships. David Laganella's Under Ethereal used instrumental techniques usually associated with wispy, happy things to explore dark, ugly things. These composers had much to say, with the boldness that comes with still-limited expressive means.

Contact music critic David Patrick Stearns at dstearns@phillynews.com. Read his recent work at http://go.philly.com.