There was something a bit perverse about the chamber-music program presented by the New York Philharmonic at the 92nd Street Y on Sunday, part of its three-week Rachmaninoff festival. Sure, the promise of the breathtaking pianist Daniil Trifonov joining forces with the violinist Sheryl Staples and the cellist Carter Brey in the seething “Trio Élégiaque” (Op. 9) was all it took to fill the Kaufmann Concert Hall. But to round out the program with two unfinished string quartets — works that Rachmaninoff abandoned, surely with good reason — when there is a luscious, masterly cello sonata begging to be played?

The emotionally charged performance of the trio, with its moments of heated passion and abject desolation, hinted at a special chemistry among these players, and Mr. Brey and Mr. Trifonov would no doubt have done wonders with that sonata. But at least one of the quartet fragments was here a psychologically revealing marker in the musical development of a composer whose chamber music often absorbed his darkest moods.

The Op. 9 trio begins and ends with a somber procession. In between, there are soulful string melodies and magnificent outbursts of pianistic virtuosity, which Mr. Trifonov dispatched with balled power and ringing tone. But most memorable was the end: the strings’ sound drained of vibrato, the piano’s hooded and wary.

The same ashes-to-ashes arc governs the slow movement of the String Quartet No. 2, for which the violinist Michelle Kim and the violist Cynthia Phelps joined Ms. Staples and Mr. Brey. It takes the form of a passacaglia on a pessimistic bass line that creeps up three steps and back again, with the viola responding in little shudders. The music grows more emphatic but never manages to shake the sense of futility to which it succumbs.