THIS is a curio. Aram Khachaturian is best-known for the big, sweeping themes in his ballets Gayaneh and Spartacus and for his splendid Piano Concerto, somewhat underplayed these days. He is pretty much completely unknown, however, for a series of large-scale, single-movement, hybrid pieces that he called Concerto-Rhapsodies. There are three of them, and this new recording, with violinist Hideko Udagawa, the Royal Philharmonic Orchestra and Alan Burybayev conducting, features the 23-minute Concerto-Rhapsody for violin and orchestra. The sizzling playing of Udagawa, which gets a bit fierce and harsh at times, doesn't altogether disguise the fact that the concerto-rhapsody, as a form, is really neither one thing nor the other. It's extremely ornamental and virtuosic music, but you keep waiting for one of the big characteristic themes to well-up – and it doesn't happen. The composer's Sonata-Monologue for solo violin is more interesting, but the plum on the disc is Sergei Lyapunov's warm, richly romantic Violin Concerto: little-known, but worth hearing.