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IMSLP

The largest sheet music archive in the world. Contains about 80000 scores and small amount of audio.
Talen:  English  
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Boxset

Lossless classic. Very big archive.
Talen:  English  
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Kunstderfuge

The world largest collection of classical midi music
Talen:  English  
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Arcadiy Chubric's mp3 archive

About 80 hours of classical music played by site autor and others
Talen:  Русский  
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Art of piano

Piano mp3 and articles about famous pianists
Talen:  Русский  
Tags:  piano

Skripach.ru

Russian site about violin. Violinist biographies, mp3, backing tracks.
Talen:  Русский  
Tags:  скрипка

Intoclassics

Classical music. Audio and Video.
Talen:  Русский  
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Alexander Nevilo's library

Sheet music and mp3 of classical music.
Talen:  Русский  
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Fagotizm

Bossoon sheet music, mp3, links, forum
Talen:  Русский  
Tags:  bassoon