GoodOlBoy, two things. I'm guessing you bought a longer cable from the Rx to the amp than you need, and that it's not shielded. This could even be acting as an antenna for noise generated by the amplifier and fed back through the Rx. Theory gets a bit complicated, but the fix might be something as simple as shortening up the cable and using shielded cable.
Also, without first scanning the particular frequency for interference, and with the luck of the draw on a used microphone set, it's just too easy these days to get frequency conflict. Digital TV uses the same frequencies as these old analog microphones.
Without having heard the static (digital TV will sound like static, not voices), it's not easy to diagnose the problem at a distance.
(Re: interference, there's been a Techpage up on Predator Masters for more than 5 years, describing how to mostly avoid this. But now the situation is only likely to worsen in the next year or so, with yesterday's FCC ruling allowing the use of "white space" for new internet wireless devices).
LionHo