Some users are experiencing an issue after upgrading to iTunes 9 where purchased content from the iTunes Music Store contains static during playback in 5.1 surround sound. The issue does not appear to affect Apple's movie trailers or DVD playback in 5.1 surround sound, though all purchased TV shows and movies from the iTunes Music Store appear to suffer the problem.
Apple Support Discussions user "DaveM777" reports:
If I put a DVD in my Mac mini the signal will get to my receiver through the mini's optical output OK, and I can hear a proper 5.1 track from the DVD. But if I buy a brand new HD movie from the iTunes store and select the surround track iTunes 9 will play static. It's not pure white noise. There is some periodicity in the static (in case that helps someone troubleshoot). If I select the stereo track on HD movie from iTunes it plays OK.
ASD user "Dave Hawkins1" provides this workaround to the issue:
I have had the "static" problem with HD versions of Mad Men, downloaded from iTunes Store. What works for me:
- Turn off the equalizer (uncheck the On box in the Equalizer window)
- Turn off Sound Enhancer (in iTunes Preference - Playback)
- Make sure your volume slider is at maximum
Most users report that sliding the volume bar in iTunes to the maximum (far right) allows for 5.1 surround sound playback, though an official fix from Apple does not appear to be available. Some users are reporting that in recent days some content purchased from the iTunes Music Store has started playing in 5.1 surround sound without having to adjust the volume (which may point to the issue being the way the content was encoded by Apple). At any rate, should an official fix be released, we will let you know.