A new and lovely fortepiano greeted concertgoers' eyes Sunday night at the Museum of American History's Hall of Musical Instruments. The Castle Trio's Lambert Orkis (also principal keyboardist with the National Symphony Orchestra) had just acquired this six-octave gem and treated the audience to two impromptus from "Drei Klavierstucke" by Franz Schubert. These are charming, romantic pieces, but the breadth of the more modern piano was missing, this fortepiano having a straighter, woodier tone. Especially interesting was the soft effect produced by the "moderator" pedal, which places a strip of felt between the hammers and strings.

The first of the two Beethoven piano trios performed, the Trio in D Major, Op. 70, No. 1, opens boldly, interspersing heroic and lyrical motifs. It features a singing cello passage that was well played by cellist Kenneth Slowik. This piece derives its nickname "The Ghost" from its spectral middle movement, "Largo assai ed espressivo," full of swooping crashes and eerie gliding strings. Orkis's fortepiano blended exceptionally well, and violinist Marilyn McDonald and cellist Slowik played a crisp and lively Presto to round it off.

Beethoven's elegant Trio in E-flat Major, Op. 70, No. 2, followed intermission, with its smooth expansive opening movement flowing into a graceful, minuet-like Allegretto. The Allegretto ma Non Troppo, heavier than most slow movements in Beethoven chamber pieces, contained some dark musings on the part of the strings. Dynamics and timbre were well observed in this trio, notably in McDonald's playing. The musicians finished in a stylish and grand manner worthy of Beethoven.