!. a sound system needs a skilled operator. You wouldn't put a fiddle on stage without a qualified player would you? Having a sound system unattended by a competent professional is asking for embarrassment and hearing damage. (same as a fiddle!)

2. Wirelss mic receivers wil amplify whatever they receive on their specific radio channel. They have a "squelch" control (usually on the back of the receiver) which will silence the random RF noise that is in the air everywhere. The operator needs to turn the system on, have the mic transmitter OFF and bring up he receiver slowly until the noise is heard, then adust the squelch to quiet the random noise, then turn on the mic trnasmitter to check the sound. Too much squelch with make the mic cut out occasionally, to little will let the noise through if the mic's signal drops, it is turned off, or the battery dies.

See why you need a professional? We are worth twice what anyone is willing to pay!