The Boston Classical Orchestra embodied its name on Friday, performing works by Haydn and Mozart, a pair with enough celebrity to attract a healthy crowd to Faneuil Hall with a program of rarities and, in one case, a kind of premiere.
Haydn's Symphony No. 40 is lesser-known among its 100-odd brethren, perhaps, as music director Steven Lipsitt wryly noted, because it lacks a marketable nickname. Invention still abounds: A charmingly sparse andante - strings only, a melody over steady footfalls - gives way to a wind-spiked minuet, a return to the ball after a flirtatious stroll. The performance was colorful but boxy, phrases blocked out more than shaped. In the finale, a brisk fugue tuckpointed with classical sequences, the groove proved initially elusive; the movement was encored without conductor, Lipsitt joking to the audience that it would sound better. It did - having found the tempo, the ensemble gave the music a fleet, coursing elegance.
The premiere opened the concert: a "Divertimento" transcription of Mozart's four-hand Piano Sonata in B-flat major, K. 358, by flutist Robert Stallman. Using Haydn's ensemble - oboes, horns, strings - the arrangement only occasionally veered from a basic layout: violin melody, viola counterpoint, horn harmony. One wished for less idiomatic, more idiosyncratic moments, more typically Mozartean departures from classical propriety. (The vigorously monochromatic performance added another historical reference point, opting for a weighty, full-bowed, one-size-fits-all mid-20th-century orchestral sound.)
That paradox of perfectly appropriate audacity burst forth at the outset of Mozart's Concertone for Two Violins, K. 190 - a bright full-orchestra scrape followed by tripping ornaments in the oboes and violas. The "grand concerto" is Mozart at his most gregariously showy; if the tunes are not particularly memorable, the orchestration dazzles, going from dark-wood grandeur to lacy transparency as if by the turn of a dial.
The soloists, Peter Zazofsky and Lucia Lin (frequently joined by extensive obbligato solos from oboist Barbara LaFitte and cellist Michael Curry), form half of the Muir Quartet, so it wasn't entirely surprising that the pair played more as chamber musicians than soloists - each phrase answering the previous while provoking the next, the tone drawing inward as often as projecting outward. What was a delight was how much Lipsitt and the orchestra emulated that approach, with an engaging, graceful, flexible spontaneity. Zazofsky and Lin also had an encore up their sleeve - a Viotti duo, tossed off with the fluent, casual panache of a card trick.