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Q: itunes 12 sound not working with ac3 passthrough

I have an Intel DX79/Xeon 2,0GHa CPU  with an NVidia GTX680 graphics card. 

 

I use an HDMI output directly to a Denon surround sound amplifier. Everything had been working fine for some years however recently I reinstalled Windows 8.1 and I found the AC3 pass through surround stopped working with iTunes.  The source movies I'm using have 5.1 tracks and used to work.  Nothing but silence I'm afraid when "Prefer AC3" is selected now.   The hardware hasn't changed - simply a re-installation of Windows 8.1 with latest version of iTunes and NVidia version 359.06.  The installation is completely vanilla flavoured apart from these two packages being installed.

 

So, I added PowerDVD and tested it with a couple of BluRay disks.

 

PowerDVD works fine with AC3 pass through - the problem seems to be confined to iTunes.  Stereo mode in iTunes works fine.  I have tried the "Old Video Card" version of iTunes with no success and I have tried downgrading the video card / audio driver version to NVidia 344.75 (A version I know used to work from about a year back) all to no avail).  I also tried version 12 of iTunes and encountered exactly the same problem. I suspect that maybe iTunes and the NVidia driver aren't playing nicely together.  Has anyone else found this problem?  I've tried contacting Apple support however it produces an error with a largish hex error code and says "Try again later . . . . . ",  Any helpful suggestions are welcome!

null, Windows 8, iTunes 12.3

Posted on Dec 4, 2015 9:52 PM

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