Beautiful Classical Smaller Pieces, duo,trio,etc

Schubert,

Janacek #2 IS a terrific modern piece, and # 1 (Kreutzer) is worth mentioning too.

For modern American I would add Carter's Quartet #3 and Ives #2.

For another "modern" composer, but, composing more in a late romantic style, Schoenberg's "Verklarte Nacht" is a basic item.

I know this is intended to be a basic list, but, can we add mention of obscure or odd-ball items that are worth tracking down? In that context I would throw in Somei Sato's "Birds in Warped Time II."

I thought surely someone would of mentioned it by now, but as nobody has, I'll mention a work that belongs in all collections .

Carl Nielsen's Op. 43 Wind Quintet , up there in Mozart winds league with modernistic melody structure .

Vienna Quintet on Nimbus is good .

Borodin String Quartet No.2
Dvorak String Quartet No.12 "American"
Debussy String Quartet
Ravel String Quartet
Brahms Sextet No.2
Brahms Clarinet Quintet
Brahms Piano Quintet, op.34

+1 Borodin Quartet #2
Schubert Quartet #14 D810 The Andante movement starts out as a death march and changes to different expressive moving moods throughout, the 2nd a lilting sweet violin expressing something lighter, and more hopeful maybe, I've always wondered. Usually a movement stays within a certain context or mood but this one does not, it is really brilliant, never heard anything quite like it as it is so completely unpredictable. Wonder what he was thinking when he wrote it? This piece had such a profound impact on me when I first heard it that doesn't diminish on subsequent listening.

Think about it Tubegroover, Schubert had written more now acknowledged masterworks by his death at 31 than Beethoven or almost any other composer had by that age.
No less a figure than Brahms, who may well have been the most learned of all composers, with the music of 400 years at his fingertips, said Schubert was the greatest composer who ever lived.