iTunes - TERRIBLE sound quality - what to do?

Mac OS X 10.4.11
iTunes 7.7.1

I listened to a track on myspace ... sound quality was good.
I downloaded the track from myspace and listened to it in QuickTime ... sound quality is still good.

But then I imported it into iTunes and the sound quality was TERRIBLE.
Equaliser is set to neutral, but it sounds like the bass frequencies are 'too much' if you know what i mean and there are cracks all the way through ...

anyone know what to do?

 

Thanks a lot, man! That did the trick.
Both were enabled.