Today’s AM receivers and radios are at least as high frequency limited as the stations themselves, often more.Agree, Eli. Music, and even, speech, sounds so compressed and frequency-limited on AM, more so now than ever. I don't mind the compression, for it makes for consistency, but bandlimiting to less than 5 KHz is a real buzz kill, even for speech.
Back in the 70s, didn't WGN 720 Chicago have permission to extend out to 15 KHz?
In the ‘80s and ‘90s a few manufacturers (including Sony) made wideband AM stereo receivers that were not bandwidth limited, and the few AM stations with higher limits than 5k sounded excellent on them (if you were getting strong clean reception).
WJIB 740 (soon 720) here limits higher than 5k, I think their audio extends up to 10k, but you can only hear that difference on one of those old wideband AM receivers. I still have a wideband AM stereo Sony receiver from the late ‘80s, here in Somerville WJIB sounds at least as good as typical analog FM stereo on it.