dc audio

Hello, I'm trying to diagnose a problem with my setup that occurs at high volumes. Certain bass notes, especially ones like a hard drum kick or something with sharpness, will begin to distort past a certain volume. The sound is difficult to describe but it's almost like a flapping noise...

This is my first post so thanks in advance for anyones response, does anyone have any experiance with any newer DC Audio amps?? the 9k in perticular. Im thinking about using this to power 2 AA SMD 18s (If any one has any feed back on those it would be much appreciated as well) and i cant seem...