I just set up the same thing on my marantz. I have to say mine is a close call as to what sounds better. The MP3 stream is pretty good and maybe a tad crisper. Either way I like it with direct monode turned . In PCM the Marantz reports a bitrate of 1536Kbps – the signal is 50% while the MP3 is 100%, is this anything to do with it?
Do you audessey when you stream, what have you found best?
The Marantz remote also lets you choose between the two streams.