AT one moment during Joshua Bell's self-composed cadenza in the Brahms Violin Concerto, the 26-year-old artist reached a climax of dazzling intensity. He had surveyed all the themes of the first movement in the cadenza, warily trying alien keys, then wisely backing down. But, almost secretly, the entire cadenza had become a crescendo in itself. And at its peak, Bell burst into a section which had something approaching the monumental grandeur of Bach's solo violin chaconne. It was a great moment for this splendid violinist. For Bell, despite his wunderkind reputation, has never been showy or flamboyant. With the Brahms, he showed that rarest of all strengths, by conserving his powers. Wisely, Bell asked the first violins to move back a few feet, so that he could have his own space. It wasn't a physical space he needed so much as the dynamic flexibility. His dark-hued Stradivarius could play the richest first-movement development, the sweetest end of the movement, and the jolliest finale. But at no time did one feel overwhelmed by his technique. Rather, Bell's dialogue with the orchestra was so natural and unassuming that when he did reach those wonderful climaxes, one felt little less than blessed. It was sheer delight to see (and hear) Kenneth Jean's return. Jean has matured over the years, but he is still the friskiest conductor around. Whether the Hungarian finale of the Brahms or the slight waltz of Prokofiev's Seventh Symphony, Jean adds vigour to whatever he touches. Jean started with an engaging work based on three Georgia O'Keefe paintings by the American composer, Dan Welcher. In a way, this was like an American version of Carl Nielsen's tone-poems. Never using a single Americanism, Welcher summoned up the play ofphotographic light in the orchestra. Jean worked doubly hard for the Prokofiev. That was necessary: the Seventh has a dozen engaging thematic tidbits, but it varies from the casual to the sluggish, and not even Jean's clarity could make it come totally alive. Prokofiev was a magician, but these tricks were less aural illusion than predictable mechanics. Ken Jean tried his own tricks, but one had to wait for the Brahms to hear Jean at his most victorious.