Please excuse the dumb newbie question . . . I am in the process of upgrading my receiver from an old JVC prologic to a new Onkyo. The old receiver does not have either a coaxial or optical input for my DVD player, only RCA inputs. The Onkyo has both. Is there a difference between the two? What is the recommended connection? Please help, I am going out at lunch today to pick up the new receiver.