The Robert Mapplethorpe Residential Treatment Center now occupies the building at 327 E. 17th Street that replaced the 19th-century house whose most famous tenant was Antonin Dvorak. Just around the corner, where part of Beth Israel Hospital now stands, is the site of the conservatory that the composer ran in the 1890s.

New York marks the spot with plaques, street signs, and a statue suggesting that the great man was also a unique corporeal specimen, suffering from both dwarfism and acromegaly. The unveiling of this hunched curiosity, which I attended as a reporter some years ago, was accompanied by remarks from eminent Czech-Americans, including Milos Forman and Donna Hanover, and a concert featuring Dvorak’s great-grandson, Josef Suk.

Some of the distinction and gentility of the Bohemian still adorns the neighborhood, even though the little park, with its odd combination of downtrodden locals and uniformed medical personnel on coffee break, is rather chillingly reminiscent of Mr. Forman’s eloquent “One Flew Over the Cuckoo’s Nest.”

Dvorak died 100 years ago, but the anniversary produced only a smattering of concerts in the first half of this year. There are many events of commemoration that begin this season, however, and will lead to extended series that spill into 2005. In two weeks, I will write from the Metropolitan Museum on the yearlong celebration of Dvorak hosted by the Guarneri Quartet.

I have probably heard Anne-Marie McDermott more in the past few seasons than any other single performing artist, largely because I devotedly followed around her recital partner, the always fascinating Nadja Salerno-Sonnenberg, reporting on her quirky performances for a European magazine. Ms. McDermott was always the steady one and, over time, I developed an appreciation of her considerable talents. Some colleagues disagree, but she may be the most underappreciated chamber musician in New York today – a fact that is already changing, as she has been voted to full artistic membership status at the society.

What was exceptional in this performance was her leadership. The Piano Quintet of Dvorak is patterned on the great Opus 34 of his mentor Brahms and requires the pianist to take control from first note to last. This Ms. McDermott did with considerable aplomb, driving the string quartet hard with her confident left hand, but also rapidly changing moods for those amazing lyrical respites that permeate the piece. Ms. McDermott is also perhaps the leading exponent alive today of the keyboard theory that upstrokes are much more important than down; she exits notes as crisply as any piano teacher could ever hope for from a star pupil.

With partners like Ani Kavafian and Paul Neubauer, this was a superlative performance, sensitively romantic but never wallowing; lilting but never schmaltzy; rapidly paced but willing to stop and smell the roses. For those of us who followed the Boston Symphony during their glorious years under Leinsdorf, the inclusion of former concertmaster Joseph Silverstein was a significant link to a rich and rapidly disappearing tradition. The response from the crowd for this extraordinary effort was not simply sustained applause but a cacophony of whoops and bravos. After intermission, Edgar Meyer joined for a reading of that “other” Dvorak string quintet – not the famous one with an extra viola but the lesser-known composition with added string bass.

To be a Tcherepnin (accent on the final syllable) in the 20th century meant to be a composer. There were no less than four of note, from grandfather Nikolai at the Mariinsky, perhaps best known as mentor to Prokofiev, to musique concrete exponents Serge and Ivan. In the middle was Alexander, known primarily on this side of the pond as a concertizing pianist a la Rachmaninoff in the 1930s and an academic in Chicago after the war. His D Major Cello Sonata was given a whitehot reading by Ronald Thomas, who was matched percussive stroke for stroke by Ms. McDermott, herself a Prokofiev specialist.

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“Brahms’s variations are like an enchanted stream, with banks so sure that its waters never overflow, even in the sharpest bends,” Mahler wrote to Natalie Bauer-Lechner in 1900. It was exactly this magical quality that permeated the splendid performance of the Haydn Variations on Saturday evening by Orpheus, a unique instrumental ensemble of infectiously exuberant and ebullient players drawn from the finest orchestras in the metropolitan area.

There are no work stoppages at Orpheus, no vituperative contract negotiations, no squabbles over parking spaces. Instead there is harmony and, although the players may disagree in rehearsal over style points, the end result is thrilling. At Orpheus, musicians who occupy the coveted principal chairs at other New York bands, for example the Met orchestra or St. Luke’s, happily play second fiddle in this true democracy, which rotates its players like a volleyball team.

This Brahms was raw-boned and extremely taut. My only quibble related to interpretive consistency. The group chose to emphasize compositional technique by taking significantly long pauses after each variation. Fine, but the same careful cerebration did not go into the planning of variegation; the individual sections sounded almost identical stylistically. If we are to experience the depth and breadth of Brahms’s variety, the strings must be more opulent in spots, the winds more emphatic in others. Instead we were treated to excellent music making during each iteration but the same type of attacks throughout. Still, this was a superb effort. The main St. Anthony theme was utterly transformed by work’s end.

The program began with a rarity: a set of dances by Hungarian ethnomusicologist Sandor Veress. Think the sound of Bartok’s Divertimento for Strings and the form of his Dance Suite. It ended with a warhorse, but one decked out in the finest of embroidered blankets.

Garrick Ohlsson only played one Chopin concerto on Saturday evening – because of a scheduling snafu he was contracted to perform it and the Brahms First Concerto in two separate New Jersey cities on Friday night – but made amends by presenting it beautifully. There will always be an argument about this first concerto: Is it worthy of its popularity? Two aspects of the debate were emphasized and, at least for this particular evening, resolved by Mr. Ohlsson’s delicate play and the New York premiere of an orchestration by Paul Chihara.

Orpheus, with its malleability, strives to present an ensemble of the proper size for each particular piece. This was not the guiding principle of Mr. Chihara’s reworking of this problematic essay, which hovers on the border between maturity and juvenilia. Rather, he “cleans up” some of the chords and perceived murky passages in the score, the way that George Szell refashioned the four symphonies of Schumann. The result was indeed crisper, and Mr. Chihara was on hand to receive the appreciative applause of the crowd at this concert’s conclusion.

Mr. Ohlsson was simply in the zone for this reading, perhaps a result of it being his third concerto performance in 24 hours. This was a remarkable combination of the diaphanous and the powerful, the delicate and the purposeful. Like everyone outside of Warsaw, I am firmly on the fence about the piece – even Mr. Ohlsson maligns it a bit in the program notes – but this type of exquisite pianistic filigree advocates strongly for its inclusion in the pantheon of presentable concerti (one never really worried about these matters when Rubinstein played it, either).The expert interplay of the orchestra elevated their participation from the level of accompaniment to that of full partnership. Mr. Chihara must have been thrilled to hear his scrubbed new chords presented with such freshness. Although the season is young yet, this was its best offering thus far.