I began having the same problem about a year ago in a 2008 RX350 with dealer installed Lexus XM - xxm sound begins to fade in and out, then sound lost, xm radio still shows signal (song and artists). Have to turn off engine to "reboot". Happens every few weeks now, I never bothered to check with dealer based on the responses on this site. Yesterday same thing happened, but I tried something and it worked; when I lost the sound, I repeatedly pressed the AM/SAT button rapidly about 20-30 times so it went through AM, SAT1, SAT2, SAT3 and for ssome resaon I got my reception back.