The lyric beauties of Schubert's Trout Quintet -- its elemental rhythms and infectious melodies -- make it a source of pure pleasure for almost all music listeners. But for students of musical forms and would-be classifiers, the work presents its problems. Since it requires only five players, it would seem to fall into the category of chamber music -- yet it calls for a double bass, an instrument generally regarded as symphonic. Moreover, the piece is written in five movements, rather than the conventional four of most quintets, and this gives the opus a serenade or divertimento flavor.

The many and frequent performances of the Trout serve to emphasize the dual nature of its writing. Some renditions are of symphonic dimensions, with the contrabass given free rein. Other interpretations present the music as an essentially intimate creation. In these readings, the double bass is either kept discreetly in the background, or it is dressed in clown's attire -- the musical equivalent of a bull in a china shop. Recently I was struck anew by the divergent approaches, when in the course of one afternoon and evening I listened to no fewer than ten different performances. The occasion for this marathon: Angel's long awaited reissue in its ``Great Recordings of the Century'' series of the Schnabel-Pro Arte version. Let me say at the outset that the music sounded as sparkling on the last playing as it did on the first.