I received an Amazon FireTV Stick the other day, and I cannot for the life of me get sound through my RadianceXD. I've tried everything I can think of; with and without the HDMI extender, with and without an HDMI switch, etc. Everything else works fine, from the Open Source Scan Converter, through modern videogame consoles, to my Apple TV 4.
The only way I've been able to get sound is to run it through my Oppo BDP-103, which is connected to my amplifier via stereo analogue. It's a bit of a pain to do it this way (turn on the Oppo with Eject so it doesn't play the disc in the tray, switch to that rear HDMI input...), so I'd love to hear suggestions as to how to solve this. I've turned on stereo sound output on the Stick, turned CEC and such off, etc. Please help