Complex sentence: The studio album "Christmas Song" was released in late 2007 and features guest vocals by Johnny Mathis and Olivia Newton-John, but co-founder Jackson Berkey is absent from the lineup.
Split into simpler sentences: The studio album "Christmas Song" was released in late 2007 and features guest vocals by Johnny Mathis and Olivia Newton-John. However, co-founder Jackson Berkey is absent from the lineup.