In Arlington's Vietnamese community, the Nguyen family is something of a legend. Not only have all five offspring absorbed their father's instructions on how to be Vietnamese virtuosos, but they have stretched their musicmaking through modern attitudes and amplifiers.

At Lubber Run Amphitheater Tuesday night, the Nguyens played tunes with names like "Heart, Heart, Where Are You?" and "Evening Sun" on souped-up Vietnamese classical instruments. Perhaps inspired by the piano, or by his adopted country's fondness for volume, Nguyen Dinh Nghia has chiseled bigger slats for his native xylophone. On this model, with its wider tonal sweep, Nam Phuon and Doan Chang tackled one of their father's pieces with sisterly cooperation. Nguyen's "Celebration" was in itself a curious convergence, deploying Haydnesque broken-chord accompaniments. A mood of subdued reverence imbued the music, helping audiences transcend son Nghi's occasionally intrusive bass guitar and some nasty shrieks emitted by malfunctioning sound equipment.

Though Vietnamese legend has it that the dan bau, the one-stringed violin, was given to man by immortals, Nguyen evidently thought he could improve on it by adding a megaphone at the base. Although amplification distorted the instrument's subtle harmonics, Nam Phoon's deft, long-breathed solo lines were a highlight of the evening.

Specifically created for ensembles of three or four, much of the music the Nguyens played can truly be called wonderful chamber music. At times, however, the younger Nguyens were a backup band for their father as he whipped through a series of trills and tricky circular-breathing exercises. Even the most musical birds represented in "Love Tryst" would have been hard pressed to match his melancholy virtuosity.