My old house had crappy wiring, and I had a couple of Morley hum eliminators on equipment that gave me problems. Interestingly, some devices didn't need them, but my Yamaha S80 had terrible problems, and one of my FX units (maybe TC M2000?).
I just looked up "hum eliminator" on Musician's Friend and the models I had were "Ebtech, by Morley"
I'd say before you go buying extra stuff like that, make sure your grounding issues are addressed, and try balanced cables between that device the the mixer.