It's perfectly understandable that you might find Mozart's last chamber work on a program of last works. In the Philadelphia Chamber Music Society's second of three "late style" concerts at the Perelman Theater on Monday night, the program's second half was given over entirely to the Quintet for Strings in E Flat Major, K. 614, written – as the program note reminded us – as Mozart was contracting the illness that would end his life.

Musically, though, not to mention emotionally, it was an enervating slip of programming. Coming on the heels of three other works operating at great intensity, all played at a lofty level, this Mozart came off as a lightweight -- merry and pleasant, but not exceptional.

It's not as though  the Brentano Quartet plus violist Hsin-Yun Huang were able to offer any special insights in the Mozart. In fact, the first movement, a hunt, seemed to be constantly struggling to catch up with itself.

For sure, the rest of the program set expectations high. The Brentano was in dreamy form in five selections from Gesualdo's Madrigals Book VI. These works, from 1611 and recently arranged for string quartet by Bruce Adolphe, live in two worlds simultaneously -- instrumental but unmistakably vocal-sounding, ancient and yet infused with dissonance and a sense of flouting the rules. There is an underlying bipolar aspect to them -- mercurial flashes of motion, a stream-of-consciousness that grasps for traditional harmonic conventions only to be thwarted. It ends up feeling like strange time travel -- the avant-garde heard through a medievalist's lens.

Pianist Jonathan Biss opened with Schumann in an unusually unsettled state, even for him. The Gesänge der Frühe  -- Songs of Dawn -- go from a hymnlike opening to strange repetition to nervous triumph in the first three movements. It's difficult not to make a connection between the breakdown Schumann was experiencing at the time and the feeling in the fourth movement of sand slipping through your fingers -- like so much reality.

If Mozart did not see death coming, and Gesualdo and Schumann were coming undone, Brahms near the end was thumbing through the chapters of life in his six Opus 118 Klavierstücke. The opening movement rushes in like youth. The fifth glows with autumnal dignity, with a section unlike any other I know in Brahms in its carefree, nearly improvisatory feel, a flashback to a simpler time.

The last movement, the Intermezzo in E Flat Minor, brings the chill of death. It's not just the literal sign -- the hint of the dies irae -- that makes this music so frightening. It somehow portends, in mood, the Second Viennese School in all its bleakness. Biss seemed to hear death, too, in the way he handled certain gestures -- arpeggios of a cold wind, and melodies of unbearable solitude.

The last in PCMS's "late-style" concerts, at 8 p.m. Monday at the Perelman Theater, Broad and Spruce Streets, features Biss in Schubert's Piano Sonata in A Major, D. 959, and, with tenor Mark Padmore, Schubert's Schwanengesang. Tickets are $25, $10 for students. 215-569-8080, www.pcmsconcerts.org.