I noticed a sound problem too. Sometimes it sounds like there's a buzzing/scratching noise that shouldn't be there. This is called "clipping." It was a problem many people think is present on the debut album for Billy Corgan's new band Zwan. I will try to describe it as best I can here:
If you were to open up one of the song files in an audio editing program such as Soundforge or Goldwave, the song would be represented by a bunch of peaks and valleys. Naturally, the very tip of the peak should come to a point. However, if the peak is flat then that means the sound has been "clipped" and that's when you will get the buzzing noise.
Hope that helps. I'm not sure how many of you know what I'm talking about with the peaks and valleys thing, but I gave it a try LOL.