Proms 2012: Royal Academy / Juilliard Orchestras, Albert Hall, review Trust the Proms to think big. Why offer just one of the world's great conservatoire orchestras when you can offer two, drawn from different sides of the Atlantic, fused together in one heart-warming display of youthful talent? Which is exactly what the fourth Prom gave us. The combined orchestras of the Royal Academy of Music in London and the Juilliard School in New York made a wonderful impression of open-handed extravagance on the Albert Hall stage. I think I counted 11 percussionists in the opening piece, Respighi's Roman Festivals, with everything else in proportion. Respighi's evocation of Roman circuses, pilgrimages, harvests and feasts is so outrageously over-the-top you just have to abandon all scruples and enjoy it. That was easy in this performance, which made Respighi's Hollywood-epic orchestral colours glow and glitter. The conductor John Adams was clearly enjoying himself as much as the players. Reckless intensity is what one expects from young players, and one could certainly feel it in the big serenade-like violin melody in October, which cut through the Albert Hall like a ray of hot Mediterranean sun. But this orchestra was amazingly strong in depth, too. In Respighi it was the principal horn Francisco Gomez Ruiz who impressed; in the Ravel Piano Concerto which followed it was clarinettist Liam Burke. He flung out his solo in the finale with gleeful panache, but overall the much-reduced orchestra played with delicate tact, just right for the soloist Imogen Cooper. She was less ostentatiously brilliant than some pianists in Ravel's jazzy passages, but she floated the long melody of the slow movement with lovely grace. Then came the evening's real challenge, John Adams's own City Noir. Adams's programme note prepares us for a moody evocation of the Los Angeles of Raymond Chandler novels and films noirs. But what makes the piece so rewarding is the way it exceeds its own agenda, in strange and surprising ways. The dark becomes too intense even for LA: there are times when we seem to be in Captain Nemo's undersea world. The performance wasn't spot-on throughout. Young players are liable to be cautious as much as reckless, and in the frenzied rush at the end of the first movement they seemed more concerned to be exact than impassioned (as did the conductor, in fact). The middle movement was most successful, evoking with thrilling intensity a sense of menace, loneliness and "darkness visible."