Most of the players are coming with Dolby Plus decoders built in; some of the new players are coming with DTS-HD decoders built in. DTS says they do not want the decoding to happen inside the player, but to only decode the signal in-side the receiver/pre-pro. A lot of the new players will let you decode the DTS-HD signal in the player, but when receivers and pre-pro’s start coming out with decoders built in this feature may go away.
You can send all the audio over Digital coax or fiber optic, but the Dolby Plus/DTS-HD will be down graded and sent over. So you can still get the audio but you wont get the benefits of the new audio formats. If you get a player with the decoders built in, the players should decode the single and sent it over analog RCA’s. 7.1 or 5.1 RCA outs will depend on what the manufacture decides to do. Samsungs player has both decoders built in, Sony’s is supposed to have both decoders built in, and Pioneers Elite player was only going to have the Dolby plus decoder built in.
Best way to do it would be to decode the audio in the player and sent a PCM audio single over HDMI to your pre-pro.