When Reger submitted his Clarinet Sonata op. 107 for printing, he remarked: ''You immediately notice that the work was originally for clarinet (viola) but that it can also be played by violin and piano.'' He wrote the violin part himself, adjusting it to suit the needs of the violin. Even before the first performance of the original for clarinet, he had tried out the work with a violinist. ''Should the critics claim once again that it is incomprehensible - then these gentlemen are simply first c