Radio playing....but no tuner?

This is a strange problem in a strange system. The setup is for an electric drum kit. Alesis is the brand. Their high end module from a few years back. It outputs to a nice but older Onkyo Integra home theater unit which drives a couple of cheap bookshelf speakers and big B&W powered subwoofer. It does not sound as good as headphones but it all works perfectly fine for my meager purposes when I want to play without headphones.

When I turned the system on yesterday to practice there was a pop radio station playing faintly through the speakers but loud and clear enough to be annoying.

The thing is that there is no tuner plugged into the Onkyo which has no built in tuner. There is no tuner/radio in the drum module either. I turned the drum module off and the radio is still playing through the speakers. If I unplugged the output from the drum module the radio stopped.


Anyone have any idea how this could happen?

It did not reoccur when I played today. Nothing else was changed.

Thanks,
George