When Indian classical virtuosos join forces, the music becomes something of a challenge match. In a trio with sons Vajhat and Shafaat, legendary surbahar performer Imrat Khan played against the tala (basic rhythmic idea), repeating it in such a way that his rhythm seemed to go astray for several beat cycles. When he landed miraculously on the first beat of the next cycle, a collective gasp swelled in the audience at Baird Auditorium on Saturday. They had experienced the same thrill we get from watching a tightrope walker end a balancing act with a graceful leap upright on the wire.

But for the Khans, music is never simply a ravishing of the senses. Classical purity is foremost in the way they shape a raga (the drone-based improvisation). This eminent musical dynasty may be known for its unassailably traditional material, but its members also demonstrate astonishing individuality. The program opened with the raga "Mahuvanti," said to be suitable for hearing in early evening. Sarod player Vajhat Khan lavished special attention on textures and dynamic contrasts. He manipulated fragments in a way that built excitement about wonderful things to come. Backing him up and egging him on, tabla player Shafaat Khan explored the rhythmic intricacies of percussive sound in a way that was both intellectual and poetic.

In his solo on surbahar, the bass sitar invented by his family, Imrat spun out a wealth of dark, rich colors over a range of four octaves (as opposed to the sitar's three). He exploited the tension between the alap melody's free-floating, unmeasured quality and the raga's regular meter. The vocal influences on Indian music were wonderfully apparent in the wailing vibrato he created by pulling the strings sideways.

Unlike Western classical musicians, who attempt to re-create the composer's intentions, the Indian musician creates his own music within given bounds. In their combinations of set pieces -- the ragas -- with personal ruminations, the Khans prove to be creators as well as performers.