Simplify the following text for a Grade 10 native English-speaking person.
Original: Under him , the orchestra increased its recording profile and became one of the leading ensembles in Europe , and gained a name for its interpretations of late romantic and 20th century works , especially those of Sibelius and Gustav Mahler .
Simplified: The orchestra became known for their playing of late romantic and 20th century works , especially those of Sibelius and Gustav Mahler .