Studio 1737 Audio issues

Own a Dell Studio 1737..know all about the issues with this laptop..have done the work arounds (Disabling a band etc...) the crackling and popping seem have been sorted but has anyone noticed that no matter what you play be it a cd or a download (Even at 320mps) the audio seems to kind of "weave in and out" i know that's not a great description of what it sounds like but it's a very subtle kind of difrerence in volume kind of like a wave or a fluctuation...anyone elase experience this..like I said it's very suble but the audio does not seem to be playing at a constant volume...any suggestions?