Interesting bug I believe I've discovered with the program. Unlike most iphone music streaming apps, the SiriusXM app doesn't automatically rebuffer when the phone switches from 3G to Wifi and back again. Consequently, I've been able to reproduce rather consistently a 128 kbps sound quality stream (only supposedly available via Wifi) over 3G when I begin the stream in a Wifi environment and walk out of range into 3G coverage. The reverse seems to be true as well.

The native 3G sound stream is okay for small speakers, but unacceptable in my opinion for even the cheapest of headsets. I don't blame SiriusXM for the crappy quality, although adopting different codecs for compression would help this a lot. It's really an AT&T thing.

Anyhow, just interested to see if anyone else has encountered this or is interested in attempting to confirm my suspicion.