I'm really amazed that people will go on and on about "radio professionals" caring about audio quality when AM radio still exists.
When AM was the only medium for music, stations spent enormous amounts of money to try to get the best sound possible out of the pre-NRSC bandwidth. Devices like the Audimax and Volumax came in the early 60's and were followed by the first multi-band processing setups in the early 70's... stations making their own processing gear using two or three LA-3A's and speaker crossover networks were common. The stations sounded good, too, without the 10 kHz mask, particularly if they had a nice broadbanded antenna system.