I've isolated some crackling noise coming from the XMD unit I have. While I'm listening to the stations, it's fine. Clear sound, crisp, no interference. However, when I switch from XM to MP3 in my front end (RoadRunner) I hear crackling sounds occasionally coming from the speakers. Since I never heard this before the XMD was hooked up, I decided to output the XM unit to different speakers.

This verified the XM was producing the crackling noise. What's the cause behind this? It doesn't happen when the music is playing (at least from what I can hear), but as soon as the XM is told to stop outputting audio (still plugged in/turned on, though) that crackling comes back.

I tried to search the board to see if this was a problem, but I couldn't isolate any noise instance in the threads similar to mine. Everyone else seemed to have alternator whine.