No sound via HDMI?

Well, you likely need to 'test' whether the issue is w/ the HDMI cable and/or w/ your MBP? A 25' cable is a 'long one' and could be the issue; also, in looking @ that cable on Amazon, there are a LOT of 1* reviews also suggesting that the cable could be the problem?

Not sure about the results in your System Preferences menu - did you have that choice when first used and are you getting video from the cable?

I would probably obtain a good quality 'short' HMDI cable and determine if that works w/ your laptop; and of course you could test the longer cable using another computer - probably of little help, but just trying to localize the problem. Good luck and let us know your solution! Dave

 

Well, I don't believe that you mentioned a 'Mini DP Adapter' in your initial post - might have helped? Was this the setup in your first use of the HDMI cable? If this is just a video adapter, then getting sound would be the issue - please more clearly describe your connections from the computer to your intended output device - I'm just confused about what you are trying to achieve? Thanks -

 

The Mid 2012 MBP does not come with an HDMI port, so he must use an adapter.

 

Sorry - my misunderstanding - just bought a MBP in April w/ an HDMI port - assumed that one from just a year ago had the same port - thanks.

 

You bought a rMBP, he has a cMBP.