Sergey Ostrovsky is a solo violinist, conductor, founder and first violin of the Aviv String Quartet for 27 seasons, founder and Artistic Director of the ‘Ensemble Symphonique de Genève’ and has taught violin at the Haute Ecole de Musique de Genève and Neuchâtel since 2009. He was First Solo Violin of the ‘Orchestre de la Suisse Romande’ from 2007 to 2012. He was also First Solo Violin of the ‘Orquesta de la Communidad Valenciana’ from 2012 to 2015.

Sergey Ostrovsky won the Grand Prize at the 3rd Melbourne International Chamber Music Competition. He is a laureate of the Bordeaux International String Quartet Competition, 2nd Prize winner of the ‘Schubert and Modernity’ International Competition in Graz (Schubert Prize), as well as a laureate of the ‘Prague Spring’ International Competition and the Rodolfo Lipitzer Prize.

As a soloist, Sergey Ostrovsky plays with prestigious orchestras such as the ‘Orchestre de la Suisse Romande’, the Israel Philharmonic Orchestra, the Geneva Chamber Orchestra, the Cape Town Philharmonic Orchestra, the Amadeus Chamber Orchestra (Poland), the Bournemouth Symphony Orchestra, the ‘Orquesta de la Communidad Valenciana’, the Jerusalem Symphony Orchestra, the ‘Luzerner Sinfonieorchester’ and the Israel Chamber Orchestra.

A passionate conductor, Sergey Ostrovsky is regularly invited to conduct in Switzerland, Spain, Russia, Estonia, Ukraine, Armenia, Georgia, Latvia and Israel.

In 2015, Sergey Ostrovsky created a string ensemble, the ‘Solistes de Neuchâtel’, and in 2023 the ‘Ensemble Symphonique de Genève’. Sergey Ostrovsky's role as artistic director of the’ Ensemble Symphonique de Genève’ is multifaceted, both as an ‘artistic manager’ and as a musician ‘involved’ in the performances. From the latter point of view, he will be able to conduct the orchestra from the podium but also conduct the violin as a soloist.

As a chamber musician, Sergey Ostrovsky has played in the world's most prestigious venues, including Carnegie Hall, Alice Tully Hall, the Louvre Auditorium, the ‘Théâtre du Châtelet’, London's Wigmore Hall and the Sydney Opera House. His ‘Aviv String Quartet’ has also made numerous recordings (Hoffmeister, Dohnanyi, Shostakovich, Schubert, Schulhoff, etc.), some of which have received critical acclaim.

Céleste Klingelschmitt is currently pursuing an Artist Diploma at the Conservatoire National Supérieur de Musique et de Danse de Paris, where she studies with Stéphanie-Marie Degand and Julien Szulman. She obtained her Master’s degree in Violin with highest honors in 2024.

She has recently performed Mozart’s Violin Concerto No. 5 with the Orchestre Colonne conducted by Christophe Coin, Brahms’s Violin Concerto with the Simón Bolívar Symphony Orchestra in Caracas, and will perform Prokofiev’s Violin Concerto No. 1 at the Cité de la Musique in Paris in February 2026.

A passionate chamber musician, she performs with various ensembles, has studied with Claire Désert and François Salque, and has appeared on the radio programme “Générations France Musique” as part of a piano trio.

Alongside her studies of the modern violin, Céleste Klingelschmitt has devoted herself for several years to historically informed performance practice. She has worked under the direction of Ton Koopman and John Butt, and has performed as a soloist in Bach’s Double Concerto with Stéphanie-Marie Degand and La Diane Française.

In 2024, she began a Master’s degree in Baroque Violin with François Fernandez and has also studied the viola da gamba with Lucile Boulanger.

A laureate of the Fondation l’Or du Rhin, the Académie de Villecroze, the Schiermonnikoog Festival Violin Prize and the Fondation Safran, Céleste Klingelschmitt won second prize at the Leipzig Bach Competition in 2026.

Brian Isaacs, 23, grew up in Queens, New York City and started playing the violin at age four. After switching to viola in 2014 and graduating from LaGuardia High School in 2018, Brian began his studies at Yale University, where he received his B.A. cum laude in Sociology with Distinction in the Major, and his M.M. in Viola Performance as a student of Ettore Causa. Starting September 2023, Brian will be based in Berlin as a member of the Karajan-Akademie der Berliner Philharmoniker.

An aspiring viola soloist, Brian most recently won both the Yale School of Music Woolsey Hall and Yale College William Waite Concerto Competitions. As a result, he performed the Walton Viola Concerto with the Yale Symphony Orchestra in April 2022, conducted by William Boughton, and will return to New Haven in April 2024 to perform the Martinu Rhapsody-Concerto with the Yale Philharmonia, conducted by Peter Oundjian. Brian was one of eight semi-finalists at the 2021 Primrose International Viola Competition, a semi-finalist at the 2022 Kodaly International Music Competition, and a prizewinner in the 2019 Anton Rubinstein International Viola Competition. At Yale, he has also received the Wrexham Prize in Music, “awarded annually to that senior who, as a performer, has best exemplified the standards of Quincy Porter”, the Joseph Lentilhon Selden Memorial Award, given “to students especially notable for their contribution in the field of music” as well as the Terry E. and Irene A. Sharp Prize, awarded “to the most outstanding performer in the junior class in recognition of their fine musicianship and potential in the field of classical music”. He has performed as a soloist in masterclasses for artists including Misha Amory, Yuri Bashmet, Noemie Bialobroda, Alfred Brendel, Isabel Charisius, Nobuko Imai, Jeffrey Irvine, Lawrence Power, Thomas Riebl, Nadia Sirota & Nico Muhly, Steve Tenenbom, and Lars Anders Tomter. His pre-college teachers include Barbera Berg, Molly Carr, Caeli Smith, and Jonathan Weber.

Brian has been fortunate to perform chamber music around the world with remarkable musicians. Most recently, he traveled to South Korea in September 2022 for chamber music concerts in Seoul, Gimhae, and Heyri. Brian participated in numerous chamber music festivals in the summer of 2022, including the Viridian Strings (USA), NUME Festival and Academy (Italy), Geneva International String Academy (Switzerland), Verbier Festival Academy (Switzerland), Moritzburg Festival Academy (Germany), and Thy Chamber Music Festival (Denmark). He has performed with distinguished artists including Peter Bruns, Jose Gallardo, Annette von Hehn, Mihae Lee, Mi-kyung Lee, and Tony Nys. In previous summers, Brian attended the Taos School of Music, Maine Chamber Music Seminar, and NEXT Festival of Emerging Artists. At Taos, Brian received numerous chamber coachings from Misha Amory, Robert McDonald, Mai Motobuchi, Nicholas Tzavaras, and additional members of the Borromeo, Brentano, and Shanghai string quartets. He has performed in chamber music masterclasses for artists such as Simone Dinnerstein, Augustin Dumay, Lynn Harrell, Mathieu Herzog, Joel Krosnick, Michaela Martin, Fred Sherry, Gabor Takacs-Nagy, and Roger Tapping. Brian has been coached at Yale by Melvin Chen, Nina Lee, Don Palma, Wendy Sharp, Mark Steinberg, and members of the Omer and Rolston string quartets.

An avid orchestral musician, Brian joined the viola section of the New Haven Symphony Orchestra in 2019 as its youngest member and gained tenure in 2021. He has served as principal violist with several renowned youth/university orchestras including NYO-USA, in which he participated in concert tours across Asia and Europe, the Moritzburg Festival Orchestra, New York Youth Symphony, Yale Philharmonia, and Yale Symphony Orchestra. In addition, Brian attended the 2018 and 2019 New York String Orchestra Seminars and the 2020 Detroit Symphony Orchestra Summer Institute. As a member of the Karajan Academy, he will participate in the viola section of the Berlin Philharmonic for numerous performances over the 2023-24 and 2024-25 seasons.

This summer, Brian looks forward to returning to the Viridian Strings, Geneva International String Academy, and Verbier Festival Academy and participating for the first time in the Four Seasons Chamber Music Festival and Gstaad Menuhin Festival String Academy. Brian plays on a 2011 Douglas Cox viola, on generous loan from the Virtu Foundation.

Cosima Federle was born in Regensburg in 2002 and started playing the violoncello at the age of four.

At 2010 she was admitted to to the "Bayrische Frühförderklasse", Regensburg under Wolfgang Nüsslein and from 2015-2019 she had lessons with Hanno Simons in Munich. In 2019 Cosima became a junior student of Peter Bruns at the “Hochschule für Musik und Theater Leipzig” and continued there as a full student since 2020.

Her playing was enriched by participation in masterclasses taught by Wolfgang Boettcher, Wen- Sinn Yang, László Fenyö, Jan Vogler, Natalia Gutman, Boris Kusnezow, Kian Soltani, Jens- Peter Maintz, Mischa Maisky and Alfred Brendl. Cosima has won various national and international competitions, including first prizes at the "International Dotzauer Competition", Dresden, at the "Làszlò Spezzaferri International Music Competition", Verona, at “Jugend Musiziert“ and 2nd prizes at the "International David Popper Competition“, Hungary and at the "Concours International de Tremplin", Paris, as well as the Music Prize of the City of Regensburg, a special prize by the "Harald Genzmer Foundation" and a Special prize by the German "Bundesapothekenkammer".

In 2013 Cosima and her brother were one of the main protagonists of the movie "Jugend Musiziert- der Film“, which was broadcasted by various German TV channels. She is a scholarship holder of the "Deutsche Stiftung Musikleben" and the "International Music Academy Liechtenstein" and received further scholarships by the "Geneva International String Academy", Switzerland, "Musique à Flaine", France, from the "Hildegard-Schmalzl Foundation" and the "Dresden Music Festival".

Since 2017 she was an annual scholarship holder of the project "Meisterschüler-Meister" in the Neuhardenberg Castle, Berlin with Jan Vogler.

Cosima has played at several festivals, including "Musique en Été", Geneva, "Dresden Music Festival", "Festival Momentum", Stolberg and performed at Elbphilharmonie Hamburg, Stadtcasino Basel and Gewandhaus Leipzig.

She produced several recordings with the “Bayrischer Rundfunk“, “Deutschlandfunk“, “Norddeutscher Rundfunk“ and “Radio Berlin Brandenburg“.

Cosima plays a cello by Nicolas Lupot, Paris 1821, that has been given to her as a loan by the “Deutsche Stiftung Musikleben“.