One of Schumanns least known compositions is his posthumously published third piano sonata. The core of it was written in 1836, but the most interesting part, the variations based on a composition by his wife Clara was written as late as 1853, with parts only published in 1983. So this recording claims to be the first of its kind. The version presented here is with an added violin though.
Most of this boxed set is filled with the three piano trios of Schumann. These were written in a short time between 1847 and 1851, at the height of Schumann’s powers. The whole set is performed by the Ravel Trio. Naming your trio after a composer that also wrote trios is a good way to hide your ensemble from any Googler. Not that it stopped three intrepid musicians to do the same more recently: they can be found, but no trace of the performers on this recording.