iTunes uses surround by default - with no Decoder connected

iTunes trying to playback AC3 sound on Movies by default, but I don't even have a Decoder connected, so it won't run. It stucks with a blak screen. I need to switch back manually to stereo every single time to make it work.

This strange behavior happens first just on my MacPro running Lion. Now, after upgrade to Maverics yesterday all of my Macs (2 iMacs / MacBook Pro) showing the same issue. I use different 2.1 stereo equipment (Harman/Kardon, Altec Lansing) connected via analog output ONLY...! This driving me crazy...!

How can I tell iTunes to use the stereo track by default...?

Thanks in advance.