It was an exciting idea for the Boston Symphony Orchestra to follow the tidal wave of James Levine’s concert — BSO premieres of two 20th-century American works and a thrilling Brahms First Symphony — with the more intimate satisfactions of Bach (the Third Orchestral Suite, with its hum-along "Air on a G-string," and the darker, knottier, far less familiar Cantata No. 170, Vergnügte Ruh’, beliebte Seelenlust, another BSO premiere) and top-of-the-line Haydn (Symphony No. 99, in E-flat). And for a moment, it seemed as if 18th-century style were going to be taken seriously, since this concert was also going to involve the BSO debuts of two important early-music artists, Dutch conductor and recording star Ton Koopman and German countertenor and recording star Andreas Scholl. So seriously that the Bach program notes were by Emmanuel Music’s Craig Smith, who is probably the only living musician who has led more performances of Bach’s cantatas (as part of Emmanuel’s Sunday liturgy) than Koopman, and the translation of the cantata text was by mezzo-soprano Pamela Dellal, a treasured Emmanuel soloist especially admired for her singing of Baroque music.

Levine changed the standard orchestral seating plan by reverting to the 19th-century practice of deploying the first and second violins antiphonally. Koopman returned the small chamber-sized orchestra to the more usual arrangement. Still, this didn’t sound like symphonic Bach à la Stokowski. There was little vibrato. Rhythms were highly articulated. The Air was buoyant rather than richly languorous. You could hear the steady tread of the bass line underneath. And the sudden diminuendos at the beginning of each repetition of the famous melody were gently touching. Then the entry of trumpets and drum made for a lively contrast when the dancing started (two Gavottes, Bourrée, and Gigue). Too bad the playing itself was a little ragged. Where was the well-rehearsed group of the week before?

Bach cantatas are unsuited for an auditorium the size of Symphony Hall, but Scholl’s voice is not only an elegant, accurate, and flexible instrument, it’s also impressive for its size. The cantata begins in joy but quickly descends into self-torment. The last aria begins, "It sickens me to live longer." I’m not sure Scholl caught the profoundest depths of spiritual torment — his voice was too consistently beautiful. But he sang with an intelligence and a gravity that were more than enough. For this cantata, with Bach’s darker orchestral color, the players warmed up the tone. Robert Sheena stood out for his solo on the oboe d’amore.

Koopman is a very animated conductor. He bounds onto the stage. He opens his mouth roundly on every held note. He squinches his shoulders. He bounces. Whenever you catch his eyes, they’re twinkling. But if you closed your own, you couldn’t quite hear that animation. Soon his liveliness began to seem generic rather than specific in its response to the music. The Haydn had charm but no center of gravity. Koopman repeated the all too common tendency of Baroque-music conductors to rush the slow movements. Program annotator Steven Ledbetter points out "the extraordinary atmosphere" of the slow Introduction and calls the Adagio "one of Haydn’s greatest slow movements." You wouldn’t have thought so from this performance. The second theme of that Adagio is one of the most insinuating, suggestive passages in classical music; it practically purrs. Koopman made it sound pretty enough, but he underplayed Haydn’s famous wit and knowing orchestral sexiness. The "atmosphere" felt more like a vacuum. The concert ended 20 minutes ahead of schedule — many minutes too soon. Or not soon enough.

ITALIAN VIOLA DA GAMBIST Paolo Pandolfo knocked everyone’s socks off at the last Boston Early Music Festival. The BEMF brought him back in this season’s concert series for a solo recital at Cambridge’s First Congregational Church, and he confirmed his memorable first impression. For one thing, he creates the most beautiful gamba sound you’ve ever heard — a singing tone that never loses its line even when the line is decorated with an efflorescence of the most fantastic fingerings. For another, he’s an extremely expressive player. Even the most dazzling virtuosity seems interior. Most of what he played — whether Italian (his own variations to the melancholy "Aria della Monica" ("Monica’s song"), English (Tobias Hume), French (de Machy and Marin Marais), or German (Bach and Abel) — had a mournful tone, and that was even true of one of his encores ("a modern piece . . . by myself"), a haunted barcarolle, gently rocking, with the eerie alternation of timbres — a kind of keening — that’s more familiar to us when it’s created electronically.

Pandolfo is one of the world’s most imaginative musicians, both in his playing and in his programming. The entire concert was a single set, with no intermission, moving from country to country (he refers to this program as "a voyage"), century to century. At first he announced individual movements, in a seductive bedroom baritone; then he began to run different composers together, sometimes without pause. At a certain point, except for the Prelude from Bach’s C-minor Suite for Unaccompanied Cello, I couldn’t tell which piece he was actually playing. But he had me hypnotized — literally entranced. I was following without thinking.

One gem I can name was his opening improvisatory variations, which shifted elegantly from rapid-fire filigree to hieratic solemnity to hushed monody to serenade-like strumming to the final dance. Another was Hume’s marvelous "A Soldiers [sic] Resolution," with its spectacularly gauged dynamics — it was an aural kaleidoscope, the army getting closer and closer, bagpipes, drums, and echoing trumpets, before the final departure into the mist of time. The disembodied acoustic of the First Congregational Church contributed to the cinematic effects.

PRO ARTE CHAMBER ORCHESTRA music director Isaiah Jackson is an ingratiating figure. But in his user-friendly chats with the audience, he’s often too ingratiating for his own good. Lately, the Pro Arte’s programming also seems to be trying too hard to please. The most recent concert started with Beethoven’s Coriolan Overture. This may be his darkest, but, several rehearsals shy of full precision, it got such a lightweight reading, it wound up declawed. Then everything else felt more like Pops than serious musical exploration: Mozart’s delightful Sinfonia Concertante for Oboe (James Bulger), Clarinet (Julie Vaverka), Horn (Thomas Haunton), and Bassoon (Ron Haroutunian), neatly executed by the soloists but rather unshaped by Jackson; Copland’s entertaining Three Latin-American Sketches; and even Stravinsky’s delicious Dumbarton Oaks Concerto. This understated yet daring transporting of Bach’s Third Brandenburg Concerto into the 20th century, however brightly led and played, sounded oddly timid as a concert finale.

SUSAN DAVENNY WYNER’s New England String Ensemble took more chances, and they paid off magnificently. The group’s first Jordan Hall concert began with the 16-year-old Mozart’s masterly K.136 Divertimento, and that offered some of the most satisfying Mozart playing I’ve heard in years — translucent (how clearly you could hear the layering of melody in the first violins, the whirring counterpoint in the seconds, and the rhythmic pizzicatos of the violas and cellos) and elegantly intense. An appealing short piece by the Chinese composer Chen Yi, who came to the US in 1986, made an effective follow-up. Her 1996 Romance and Dance, for two violins (Christine Vitale and Biliana Voutchkova) and strings, is a fusion of Western instruments and Chinese styles. It condescended to neither — and knew when to stop.

But what made this a great concert was the stunning performances of two rarely played masterpieces of the 20th century: Benjamin Britten’s spellbinding Serenade for Tenor, Horn, and Strings (1945) and Arnold Schoenberg’s Verklärte Nacht ("Transfigured Night," composed in 1899 as a string sextet and transcribed for string orchestra in 1917), profound works of immense difficulty requiring not only phenomenal technical skill but also complete concentration and thorough conviction.

The Britten is treacherous for both its soloists. But young tenor Jeffrey Thompson turned in, without apparent effort, the most powerful performance I’ve heard from him, articulating both the text and the emotional subtext of Britten’s astonishing settings of six poems about evening (and mortality): the delightful 17th-century poet Charles Cotton’s "The shadows now so long do grow,/That brambles like tall cedars show;/Molehills seem mountains, and the ant/Appears a monstrous elephant"; Tennyson’s brilliant "The splendour falls on castle walls"; Blake’s stomach-churning "The Sick Rose"; the terrifying Scottish "Lyke-Wake Dirge" ("If meat or drink thou ne’er gav’st nane. . . . The fire will burn thee to the bare bane;/And Christe receive thy saule"); Ben Jonson’s scintillating hymn to Diana, "Queen and Huntress, chaste and fair"; and Keats’s moving sonnet "To Sleep" ("Turn the key deftly in the oilèd wards,/And seal the hushèd Casket of my Soul"). And the BSO’s principal horn, James Sommerville, playing the part written for the legendary Dennis Brain, made Britten’s challenging variety (hunting horn, solemn dirges, a lonely off-stage lament) both coherent and mysteriously moving.

The Schoenberg is a landmark work whose chromaticism and aching harmonies seem to be both the culmination of 19th-century European music and an announcement of all the musical changes that lay ahead in the new century. It was inspired by a controversial but piercing contemporary poem by Richard Dehmel about a couple who find redemption when the woman confesses that she is bearing a former lover’s child and the man accepts it as his own. Wyner led her gorgeous strings in a soul-stirring account, balancing formal clarity with a burning narrative drive. I’d be very surprised to find this concert missing from my year-end "Best of 2003" list.