A consummate chamber musician, Mr. Castro-Balbi is a founding member of the Castro-Balbi/Lin Duo with pianist Gloria Lin, a founding member of the Momentum Trio with Gloria Lin and violinist Jennifer Choi, and has collaborated with violinists Miriam Fried, Rostislav Dubinsky, Cho-Liang Lin, violist Jesse Levine, and cellists Martin Lovett. As a leading member of the Yale Cellos, he performed at Carnegie's Weill Recital Hall. He was invited to take part in the La Jolla Summer Fest in California (1999); the Norfolk Chamber Music Festival in Connecticut (1997); the Juilliard Chamber Fest (2002); and the Isaac Stern Third International Chamber Music Encounters in Jerusalem, Israel (1998).

Mr. Castro-Balbi can be heard with cellist Carlos Prieto on the Urtext Digital label (JBCC045), in the first recording of the Suite for Two Cellos by Mr. Zyman.

Mr. Castro-Balbi was a member of the Rassaert Quartet (1992-97), the Dubinsky String Quartet (with Mr. Rostislav Dubinsky, first violinist, 1996-97), and the Alma Piano Trio (1999-2001). His chamber music mentors include pianists Boris Berman, Peter Frankl, David Golub, and Joseph Kalichstein; violinist Rostislav Dubinsky; cellists Iseut Chuat, Marc Coppey, Aldo Parisot and Fred Sherry; and members of the Tokyo and Juilliard String Quartets. He performed in masterclasses for pianists Leon Fleisher, Gilbert Kalish and György Sebök; violinists Pamela Frank, Eli Goren, Peter Oundjian and Isaac Stern; as well as for members of the Amadeus, Arditti, Emerson, Orion, and Vermeer String Quartets.