Could be that you have the volume turned up too loud. Turn it down and see if that stops it. You might be over-driving the head set. The Regulator preset is a very hard driving preset. It’s much louder at default than any of the others, especially in the low end. I’m sure you found that out just by listening. 🙂
Sounds like blown headphones, mayasecret. If the transducers (whether headphones or speakers) have been played too loudly for too long, they will get damaged, and subsequently make a buzzing sound when fed a lot of bass. I’m sure you have heard this before in regular speakers 🙂.
There is no workaround other than either turning the bass down or turning the volume down. The best solution is to replace the headphones. Check head-fi.org for recommendations. 🙂
However, they’re somewhat new… and it’s only a couple of songs that buzz…
Also, the scope maxes out top and bottom for these few tunes (looks like I’m throwing Breakaway off the wall when they play =), so I’m hoping that it’s just a problem with the song…