Most AVR's cannot properly process the multi channel pcm stream. What I mean by this is if you send a pcm uncompressed signal to your AVR, you would need to increase the LFE level by 10db. This is a flaw in how modern AVR's process the stream. Some AVR's can process the the signal properly, you just have to research your AVR. Bit streaming is better because your AVR can properly process the the sound. Most games are mastered in DD or DTS to produce the proper sound for the game. PCM is an old technology for old AVR's and people who cannot or will not upgrade their AVR for sentimental reasons. There really is no reason to use pcm. Most modern TV's have DD decoders built in and take a bit stream signal from your Xbox.