I have an X1 set top box which is connected a flat screen with a sound bar. That works just fine. On the back of the X1 box is a pair of RCA audio ports. When the box is turned off (via remote), everything's off, as you'd expect. Mysteriously though, when I connect my headphones to the RCA ports, I hear audio for the last channel selected before the box was shut off !!!! To anyone (hopefully) familiar with the Comcast X1 box, how on God's earth could this be happening?