Complex sentence: Young, though bewildered by the band's sound, contributed drums: They (Malkmus and Kannberg) come in and they play this weird guitar noise and it just sounds like noise, with no background.
Split into simpler sentences: Young, though bewildered by the band's sound, contributed drums. He later recalled that (Malkmus and Kannberg) come in and they play this weird guitar noise and it just sounds like noise, with no background.