Bruno Leonardo Gelber, the powerhouse Argentinian pianist who performed last night at the Terrace Theater, is a throwback to the days of the 19th-century salon. In both appearance and music-making, he projects an utterly Romantic aura. A small, round man with a demure face, he performs in tails while seated on an open phone book atop the piano bench. Due to an early bout with polio, his left leg has lost much of its strength, and so he soft-pedals by pressing his right foot against his left, or adjusting the afflicted leg with a free hand. Then, too, there is the ethereal, uncommonly serene manner with which he eyes his audience and confronts the instrument before him.

Few artists can carry off a program of highly technical, profusely ornamented works without sounding slightly flashy or labored. Gelber is one of those few. He began with Chopin's Ballade No. 4, then plunged directly into the "Wanderer Fantasy" of Franz Schubert and returned after intermission to tackle Brahm's Sonata in F minor. These pieces share a symphonic quality, a drama and density that take one from storm to calm and back again. Gelber's shimmering tone, his passionate explorations of tempi and dynamic shadings, and the way he seemed to put musical "brackets" around particular passages, gave these expansive works brilliant clarity and shape.

Gelber never seems to be expending undue energy, yet the sounds he produces are almost frighteningly powerful. His fingers move in swift, delicate clusters, sending forth cascade after cascade of musical embroidery. One thinks of Liszt, of lace, of rushing water -- and, thanks to Gelber, appreciates Romanticism anew.