I'm not sure if what I'm hearing is the limitation of the bass on this driver, or if there is something else going on, but basically, when I hear bass notes that are around the 60Hz ang below range, I get this strange wobbling effect.

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I'm nto super sure how to explain this very well, but imagine the - symbol as bass being played, and _ being no sound. When using a pure tone generator at 60ish Hz, it sounds like ---___---___---___--- as opposed to ----------- if that makes sense. Bass will roughly play fine for half a second, fade out, fade back in, etc etc. My HD600 don't do this, and other headphones I have don't do this either. Any clues as to what could be going on here?