Any broadband connected PC can receive online radio stations. They usually have a "line out" jack socket. If they don't, but have a USB hole, for a fairly nominal sum off ebay, you can get a USB sound card that will provide the required. Just plug the line out to the amp line in, set the output level of the output to match the amps wanted input, job done.
My "record player" consists of an old PC more or less dedicated to that job, working like that. While typing this, I woke it up, went on t'interweb, told it to look for Smooth FM*, saw a button that said "listen now", and it just sat there and worked.
After the original elderly PC curled its toes up, I got fairly lucky and spotted a refurbed one from one of the companies that trades on the basis that they sell bargains, but when they are gone, they are gone. A really cheap tablet on the home network would probably do the same job.
*OK, its musical wallpaper, but generally, pleasant wallpaper.