So I don't know if this is "fixable" or not, but I run the majority of my devices into my 4k TV directly and then from the TV I run an optical cable to my receiver (as it is old and doesn't have HDMI in). For most of my consoles the TV has no issue converting the HDMI surround sound to optical surround sound and passing it to the receiver. This, however, does not seem to work for the Super Nt. As I said..not sure if it is fixable or not, but my other HDMI systems (sans the Wii U) can do it without an issue.