Complex sentence: Shortly afterwards, the last two public concerts directed by famed conductor Arturo Toscanini were recorded on stereophonic magnetic tape, however they were not released as such until 1987 and 2007, respectively.
Split into simpler sentences: Shortly afterwards, conductor Arturo Toscanini's last two public concerts were recorded on stereophonic magnetic tape. They were, however, not released in stereo until 1987 and 2007, respectively.