PICTURES AND PROKOFIEV: Mussorgsky: "Pictures at an Exhibition." Prokofiev: Sonata No. 6. Dickran Atamian, piano. Lyra House LHL 1003. RCA Victor awarded Atamian--winner of the 1975 Naumburg Competition at the age of 19--a recording contract when he was age 22. The pianist's performance of Sam Raphling's reduction of Stravinsky's "Sacre du Printemps" was issued, but RCA never released other major works he recorded. These hail from that era. Atamian's unique interpretations abound with color, force and imagination, but the same individualism that can work to hypnotic effect occasionally serves to disjoint sections. In "Pictures," he breaks chords between hands when a more granitic sound would be advantageous, and adds a quirky left-hand tremolo to the closing Grave of "The Great Gate of Kiev." Prokofiev's Sixth Sonata also emerges sensitive and powerful, if not always wholly connected.