Is it there at all volumes? Likely the CD.
There only at loud volumes? Likely overdriving a cone-STOP!

Between tracks? Again, likely the CD.

My feeling is that if a speaker is made to reproduce distortion, it can be damaging to the speaker at louder volumes. This is because you're asking the speaker to reproduce a truncated, sharp-edged waveform.

Or, maybe I'm wrong. But I still wouldn't do it to my speakers!

::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::