Zdenek Macal, in addition to serving as music director of the Milwaukee Symphony Orchestra, lists Washington, Atlanta, Houston and Detroit among the stops on his 1990-91 itinerary. Macal's busy schedule is understandable, given the dual role of elucidator and equalizer he played Thursday night as the National Symphony Orchestra's guest conductor at the Kennedy Center. Sprawling scores by Liszt and Mahler emerged with all elements clearly in place, superbly balanced as if an audio engineer were adjusting the sonics.

Before tackling the romantics, however, Macal offered "Preambulo," written by his colleague Roberto Sierra, composer-in-residence with the Milwaukee Symphony. Sierra's piece exploits rhythm and color via an expanded arsenal of percussion instruments, including suspended cymbals, bongos and conga drums. A disjointed Latin-American clave rhythm in 5/4 time gains momentum gradually while different sections of the orchestra embellish the pulse, then turn to more lyrical concerns. "Preambulo" made its points tersely and poignantly. Sierra himself appeared onstage to accept the audience's generous applause.

Soloist Tzimon Barto joined Macal and the NSO for a reading of Liszt's Piano Concerto No. 2 in A that stood out for its purposefulness and complete absence of bombast. This problematic odd duck, which by design seems more like a tone poem with piano obbligato than a true concerto, succeeded on this occasion because Barto and Macal saw eye to eye from the start. Barto's strength is his restraint; virtuosic passages took shape easily and without theatrics. If his phrasing was a tad stiff during the first cadenza, the pearly arpeggios that preceded it and the heartfelt dialogue later with NSO principal cellist John Martin dazzled gently, revealing the pianist fully in command.

Macal and the NSO applied the same care and insight to Mahler's Symphony No. 1 in D ("Titan"). If anything, they cut this "titan" down to size with a well-proportioned account of what the composer originally conceived as a symphonic poem. There was plenty to admire: the crisp attacks in the second movement; the quiet splendor of the harp-supported second theme that follows Mahler's funeral march based on "Frere Jacques," initiated by the string bass. For a work so complex and deeply personal, Macal and the NSO reached its core, allowing the audience a glimpse of what stirs the romantic sensibility.