So, I'm still new at some of the units and just picked up one of these from a guy on Craigslist. I normally don't buy car audio used unless it's from a friend and I now know why. Anyways, I've installed this unit in my '00 Lexus GS300 and the radio and XM (with the tuner box) are working but I can't get any audio from either one of the AUX inputs, the USB input, or the iPod connection. They all show that they're connected and show the audio descriptions and timers for the songs, but I don't hear anything. Does anyone have any ideas?