Re: Was I the Last One to Figure Out HD Radio on 8.4?
The truth about Sirius is that it never really sounds "good" in any car. The music is compressed to 64 kbps which - if you know about music bitrates - is really low. Some channels broadcast even lower, so some will sound worse than others. The reason for this is limited available satellite bandwidth. A quick Google search will show a general distaste for satellite radio by anyone who cares about the audio quality of their music. For those that don't care, it doesn't seem to be a concern and they can live with it.
Also note that in a higher-quality audio system, the imperfections of Sirius are going to be more evident when switching from an input like your ipod with high quality tracks on it.