The first step will be to update the firmware on your TV. I am providing a link explaining this process. Let me know the results.
Our Samsung UN32C4000PDXZA has muffled/muted sound on both HDMI2 DirecTV and HDMI3 AppleTV. Both worked great as recently as last night but as of 8 am this morning it's all muffled and even the on/off chime melody is muffled/muted (also worked fine when turned off TV at 11 pm last night).
We're out of warranty so I need to know if this is something we/tech service can fix and if so how much $$$? We bought the TV at Costco in Jan/Feb 2012. Never done any updates to operating system/software on TV. Remote is MIA (we use the DirecTV remote to operate system) but replacement will be here on Monday.
Already tried resetting sound to factory presets without success.