im not sure there is any issue here....
if you dont have say, xm or sirius, what lines that are muted before RR is started
RR doesnt mute or unmute anything explicitly on start
and this statement is odd
what are other sound devices?It would appear that when the music player is selected all other sound devices are muted.
my guess, the silabs fm tuner(someone get me one) brings its audio in via usb audio, and that dll uses directshow or some capture method to bring audio to the speakers