The two most tantalising losses for classical clarinettists are the autograph scores of Mozart's Concerto and Quintet, both supposedly lent by the composer to his friend Anton Stadler and subsequently lost. All surviving sources for clarinet misrepresent these pieces by adapting the solo part to the smaller ranger of the modern clarinet (Stadler's instrument had a basset extension to low C).

One advantage of an adaptation of such works where the piano takes over the majority of the clarinet part is that there is no restriction on range, and in the present transcriptions we can detect possible remnants of the original basset version. This arrangement by Christian Friedrich Gottlieb Schwencke also serve to enhance a side of chamber music that Mozart himself neglected, and offer players an additional piano quintet to add to their repertoire; in addition it proves a valuable source of new readings and interpretative suggestions for clarinet players performing the "original" versions.