Complex sentence: He attended the Moscow Synodal School for ten years and later studied composition with Taneyev and Ippolitov-Ivanov; after he already had a solid reputation as a composer and conductor, he studied free composition at the Moscow Conservatory with Vasilenko.
Split into simpler sentences: He attended the Moscow Synodal School for ten years and later studied composition with Taneyev and Ippolitov-Ivanov. He already had a solid reputation as a composer and conductor when he went on to study free composition at the Moscow Conservatory with Vasilenko.