Mary, I use Total Recorder to record RealAudio programs when I want to save them. The technique could also work for you even if you didn't want to save them but just wanted to hear the concert uninterrupted. When Total Recorder is recording in software mode (the mode needed for recording streaming audio), recording stops when the audio stream stops then automatically resumes when the stream starts again. Sometimes you get a little 'blip' in your recording at that point, but it's not nearly as annoying as the program starting and stopping, often for long periods.

Total Recorder is found here:

Total Recorder