Done a fair bit of reading on available decks, but must confess to being a little confused by the array of output options. Particularly re the sound. To ensure that I future proof my purchase as much as possible what should I look for. Some dealers are showing me units with the relevant array of mulitple RCA plugs others say that optical is the only answer. I always suspect a hidden agenda and would appreciate a honest answer. I am considering an amp upgrade also, so the two need to match up !