Dirk Brossé may be gradually reshaping the Chamber Symphony of Philadelphia into a mainly classical ensemble, but he is moving quickly to give the ensemble an air of informality.

He steps to the podium, microphone in hand, to speak casually to the audience, and, Sunday in the holiday concert at the Perelman Theater, he introduced the new concertmistress, Miho Saegusa; the new principal viola, Beth Guterman; and four other new players.

The soloist, hornist John David Smith, is also from the chamber orchestra. Brossé further said that while he once felt in a foreign land when arriving in Philadelphia, he now felt as if he were coming home.

Anonymity is a curse of the orchestral tradition. It's easy to speak of "the orchestra," when, in a chamber orchestra, individual presence and identity give distinction to the ensemble's sound and interpretive ease. After the introductions, listeners may have felt they should have said "Hi."

Brossé's program defined his classical bent. Mozart; his father, Leopold; and Mendelssohn are musical cousins, prospering through transparent orchestration, clear forms, and winning melodies. Brossé's ensemble responded with transparent balances, and the interpretations grew from shadings, subtle lights and shadows, agility, and quick insights.

If his conducting sometimes bends toward anonymity, he does not seek identity through distortions and out-of-context flourishes. His music grows organically, often gracefully, and in identifiable style.

The collaboration of conductor with the horn soloist in Mozart's Concerto No. 4 gave distinction to the performance. Smith has an appealing lyrical mode built on varieties of softened attack and seamless phrasing. The work seemed an extended song, with some declamation, to be sure, but with high regard for the flow and shape of the work. He added some decorations, and included a cadenza which touched on bits of the work's melodies without overweighting its place in the whole. His winning technical skills seemed always guided by respect.

Brossé had opened with Leopold Mozart's Toy Symphony, a Christmas bonbon which saw members of the wind sections twittering like birds and trying to solve the mysteries of percussion.

The conductor promises surprises in each concert, and here he led a rather straitlaced reading of Astor Piazzolla's Oblivion. Tangos bend and slouch a little more than this one did. Mendelssohn, a universe away from Piazzolla, emerged with apt spirit and pace, but was memorable for its clarity. Those new players all had names in this reading, and the shifting colors of their parts invigorated the whole piece.