Reply to Xone DB4 question

I am playing on an Allen & Heath Xone DB4 with Pioneer CDJ 2000's and have noticed some wierd sounds. One of the decks has a wierd metallic sound to it. It as if there are effects running all the time even though the effects processor is off. Has anyone heard of this? I have a gig toevening and was planning on using to live for the first time, but now I'm not so sure it should be used.