That's my impression of the Audio Peter - AM of course, has it's sever bandwidth limitations - I think they are doing pretty well, to achieve what they do. Of course, some receivers, do a better job than others. Providing you are getting a strong signal, it can sound a lot better with some receivers tuned to 649 - esp Car radio's
Of course, the originating studio quality, can vary - Gary Zeipe's studio, sounds slightly square wavey to my old ears - especially his Microphone - as if there is a slight miss-match, perhaps?
Probably just my imagination I expect.