by James Leonard 　　 　　There are many listeners who have come to cherish Murray Perahia's Bach, to treasure the fleetness of his fingers, the delicacy of his touch, and the beauty of his tone. There are many listeners who are deeply moved by Perahia's recording of the Goldberg Variations, who hear tragic depths in its first groups of variations, consummate wit in final variations, and heartbreaking nostalgia in the return of the theme. For those many listeners, Perahia's recording of four of Bach's keyboard concertos will be another wonderful disc. There may be other listeners who find Perahia's technique in the outer movements of the Concerto in D major merely adequate, who find his touch in the central movement of the Concerto in F minor more feeble than delicate, and who find his tone in the central movement of the Concerto in G minor more narcissistic than beautiful. There may be other listeners who feel that Perahia's playing is sweet but superficial, who find his interpretations pretty but not profound, who find his direction of the Academy of St. Martin-in-the-Fields tolerable, but not much more.