dn-x500 denon mic channel problems?

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I'm using the EV zxa5's, about 4 weeks ago my original dn-x500 mixer went bad, so I purchased another one...

Here's the thing last wedding I did, I noticed when I talked(and only me) I can could hear a buzz,tremor noise as if something were lose inside the speaker. In playback it doesn't do that but for some reason with vocals it does.

Now question of the day is it possible that it could be the new mixers mic. channels that are bad? it's a dn-x500 as well.
Or for bad luck the speakers?

There isn't really a way for me test them at high volume at home, unless I try in a live situation.
 
Can your mic gains be too high? Are you using XLR or 1/4" connectors?