I had Sirius in my last car which I traded in 11-11. From 2007-2010 the quality was OK for the car - not great but not too bad either. In 2010 or maybe early 2011 they did a channel re-org and added more channels. This seems to have increased the amount of compression used, and the Sirius became virtually unlistenable, even casually. Sustained vocal, guitar and piano notes would actually wobble a bit in pitch, and there was a lot of distortion. It sounded a lot like a cheap cassette deck. Both my car radio and the home unit I bought gave similar results.
I didn't do Sirius in my new car and cancelled service on the home radio I had.
I didn't do Sirius in my new car and cancelled service on the home radio I had.