No Sound at all after WD Tries to play DTS Digital MKV file + Reboots my TV Vizio M221NV

Well, that’s correct.   If you select STEREO, it will downmix the DTS to stereo.  My guess is, when outputting certain audio modes to your TV, your TV’s audio decoder dies, and the steps you’re taking forces the TV’s HDMI to reset the decoders.  And really, it shouldn’t matter if the WDTV outputs random GARBAGE out the HDMI… your TV should not reboot.   THAT bug is your TV’s.