I had the same problems until I followed this solution:
Hope it works. It just did for me!
Totally fixed my sound issues! Thanks! d-.-b
iTunes 11.0 is fine, my music is fine - it is the Equalizer / preamp that that is not so good...
iTunes > Window > Equalizer -
Suggest you keep the pre-amp at zero or below, and don't go much above 6db in any range
Alternatively, just turn off the Equalizer by unticking the "on" box
I was going to post the same; well done, I thought it was only me that found this. Yep, that works a treat.
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