Thanks for your quick reply, 2000CAD. 'Internet Radio' is a selection under 'Library' when iTunes is opened. It's under 'Artists,' 'Albums,' 'Songs,' and 'Genres' in my iTunes sidebar. The main window contains a list of stream categories, e.g., 'Blues,' 'Classic Rock,' and so on. Opening 'Classical' reveals a list of a few hundred providers, including (reverse alphabetic order) WYSU, WXXI, WWFM, WUIS, and so on. Until a few months ago, clicking on WWFM took me to the site; the content was the same and basically in synch with what I heard on my FM radio. The station upgraded its digital feed and had a few growing problems. It is now accessible at http://wwfm.org/classical-music-stream via two streamers: aacp - https://wwfm.streamguys1.com/live and mp3 - https://wwfm.streamguys1.com/live-mp3.
The WWFM page also contains the following:
"Please note - if you are using a third-party app, such as Tune-In Radio or iTunes, we have little control over technical issues, provided our regular stream is working correctly. Please refer to the app or device's customer support."
I have confirmed that Tune-In Radio (on my iPhone) and the aacp and mp3 sources work, but the Internet Radio stream on my iMac iTunes is dead. How can this be fixed?