While he was a student, from 1996 to 2001, Sevastian joined the Russian Radio Orchestra in Moscow, and with the support of the conductor Nikolai Nekrasov he became a featured soloist touring throughout Russia, Ukraine, Germany, Italy, and Japan. From 2002 until 2018, as a member of the mixed instrument classical crossover ensemble
Quartetto Gelato, Sevastian recorded five CDs, and toured every province in Canada, almost every state in the US, and many countries around the world including Russia, Korea and Mexico, The Bahamas, and Guatemala. With this ensemble, Sevastian performed traditional classical and folk works for accordion, as well as arrangements and new compositions. In November 2002 he made his solo debut under Boris Brott as a soloist with the
Hamilton Philharmonic, and then in April 2008, debuted with the
Toronto Symphony under the baton of
Peter Oundjian, performing the
Malcolm Forsyth Accordion Concerto at the New Creations Festival. He went on to perform this work with the orchestra on their 2009 tour of Eastern Canada. He later performed as soloist with the Calgary Philharmonic Orchestra as well with other orchestras in Canada including Victoria, Quebec City, Kelowna, Kamloops, Windsor, Edmonton, Mississauga, Nanaimo, as well as Charleston and Sioux City in the U.S.A. After winning the Coupe Mondiale International Accordion Competition in 2007, his fourth major competition win, his solo recital career blossomed. He toured extensively, performing often at prestigious music festivals in Canada, and in Russia, Belarus, Ukraine, Germany, Japan, Mexico, Italy, Portugal, Serbia, and the US. Highlights of his career included appearances in the Tchaikovsky Concert Hall, Glinka Capella Hall (St.Petersburg),
Suntory Hall (Tokyo), Minato Mirai Hall (Yokohama),
Roy Thomson Hall (Toronto), Jack Singer Hall (Calgary) and
Metropolitan Museum of Art (New York). Sevastian gave several premier performances of new works, including ones by Russian and Polish composers Sergey Berinsky, Mikhail Bronner, Vladimir Nikolaevich Korolchuk,
Władysław Żeleński and Japanese composer
Jo Kondo. Before his death, he had begun playing with Toronto's Payadora Tango Ensemble and was also acting as a promoter, bringing in musicians from Russia including Bayan Mix. ==Awards==