Eric Logan should address the sound quality of XM in general. The promise of "CD quality sound" is the biggest lie going with both of the satellite services. Neither are anywhere close to CD quality sound. Hell, my MP3's sound better and I would contend that most channels are just above cassette tape SQ level.
Both services are screwed. To make money they have to have a lot of channels and to do that they have to sacrafice bandwidth per channel. It is pretty clear that give some channels more bandwidth than others, but none are the promised CD quality sound.