BEHRINGER FEEDBACK DESTROYER QUESTION

2020-10-27

I have bought a Behringer feed back destroyer FBQ1000. I have a Yamaha MG16XU mixing deck with electro voice ELX115P powered speakers . when i connect the FBQ1000 to the FOH speakers, I can hear a hissing sound like the FBQ1000 has introduced gain into the circuit. when i remove the FBQ1000 and connect the speaker directly to the mixing deck the hissing goes away. is the FBQ1000 working correctly or is there something i can do to remove the hiss ?