My understanding is that it’s basically the same as ripping a CD - I have a perpetual license for personal use.

Of course if I broadcast it publicly or share it on bittorrent I am in violation. But if all I do is keep it in my music library for myself to listen to, it’s OK.

So, while the MP3 is covered by an Amazon license and the ripped CD has an implied fair-use license, those license terms are more-or-less the same.