Does anyone know the title of an older Hit man / Proffessional

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Does anyone know the title of an older Hit man / Proffessional killer movie, where in the beginning the main character is practicing violin in his apartment but some dude is beating a hooker outside and the protagonist asks him to be quiet, and eventually kills the guy and brings the woman into his apartment, where she finds it has a secret room in back where he keeps all his expensive shit, and eventually the mob related the the noise maker comes after him and breaks into his apartment and kills the girl. several killings and events follow but this is about all I can remember. I'd really like to know the name of this movie if anyone can help. Thanks in advance. Pic related I'm positive it isn't an Agent 47 movie.