When Franz Joseph Haydn began focusing on the genre of the piano trio, such pieces were technically and intellectually undemanding bagatelles crafted for at-home entertainment among the middle and upper classes. Haydn changed that. His approximately 45 piano trios basically defined the grouping as a central medium of chamber music, especially through the brilliant examples he produced during the 1790s. The Trio Wanderer, one of the world’s leading self-standing piano trios, offers fine readings of five of those mature works (Hob. XV/14, 18, 21, 26, and 31). The ensemble is most associated with 19th-century music, and these interpretations do seem to approach Haydn’s trios from that direction, finding in them proto-Romantic expressive possibilities. Their readings don’t turn their back on wit and humor, which are built into so much of Haydn, but here those qualities are concentrated almost exclusively in the finales, most endearingly in the Presto of the C-major Trio. If you’re principally looking for laughs, this may not be the recording for you; on the other hand, it reveals depths not universally imagined in these pieces. The group’s serious, shadowy approach is especially effective in the slow movements — the Andante of the A-major Trio is a marvel that here looks ahead to Schubert — and in the two of their selections set in minor keys, particularly the intense Trio in F-sharp minor.