PCM 2.0 My Bose 321 System shows PCM 2.0 when I watch TV (DirecTV). I have a friend that has the

Question

My Bose 321 System shows PCM 2.0 when I watch TV (DirecTV). I have a friend that has the same system and his display reads "Dolby Digital 5.1". He says that it has better surround sound than mine when watching TV. How do I change mine from PCM 2.0 to Dolby Digital 5.1?I have a Bose V20 system and the display shows PCM 2.0. Is this different or better than Dolby 5.1?