A new transmitter at the same power should not be a big deal audio processing wise, unless they changed out the STL or the exciter. Many years ago I always used the air monitor to run the headphones and studio speakers. If the music sounded wrong, sooner or later someone would notice. Now with voice tracking, HD and its digital “lag”, some of the older internet STL’s having 2 plus second digital lags, I doubt anybody at the studio uses the on air monitor anymore. The only exceptions would be translators tied to AM’s and the few non HD FM stations in the market. The receptionist can only have one station playing in the lobby. There could be stations in this market that no employee listens to the “on air signal” regularly.