With some equipment with inadequate headroom, the output voltage of the Q.Bert is too much.  This is a rare circumstance, but is known to happen occasionally.  This is not a flaw on the part of Ortofon, but instead a problem with the equipment being used in conjunction with the cartridge.  If your turntable has a built-in phono preamp (offers a line-level output), try disengaging it and using your DJ mixer for preamplificaton.  Conversely, if your turntable has a built in phono-preamp, you can also try the opposite - engaging the built-in preamp and using the line input on your DJ mixer.