My XX2 has close to 200 hours on it now. I have found setting the VTF at 2.0 and the loading at 100 Ohms to be helpful. Sometimes on the same album the sibilance can be fine on some tracks and exaggerated on others, regardless of the tracks location on the disc. Most albums play just fine. I think mixing that hypes the top end is at fault and the XX2 doesn't gloss it over. The sibilance is equal and undistorted in both channels.
Bill
Bill