Situation: I just got a DirecTV receiver with an optical out for Dolby Digital. This is connected to my "preamp" a Sony DB 930. For non DD programs I like to use either Normal Surround or Cinema Studio EX. B. I leave the receiver set to one of these settings. When the DirecTV box outputs a DD signal, I get all of the indications that the Sony is treating it as I would expect. Question: Is the receiver sending the speakers the Dolby Digital output or does it dumb it down somehow because of the other surround setting? Thanks for any input.