When you have a directional system, with multiple towers that have to be tuned, sometimes bandwidth can suffer. Just speculating with no direct facts of knowledge of this particular operation, my best guess is either the transmitter or more likely the antenna system. With all of the AM stations going "dark" a decent audio chain should not be a budget buster. The Breakaway licensed version is $200.00. The STL audio response should not be an issue for a talk station because the "stone wall" audio filters everyone was suppose to install last century should kill everything above 9.5 khz.