Veeerrry interesting, Rick!! You are obviously a 9th Dan Black Belt! I had the Shaw Cable Motorola DCT3416 DVR STB turned off, but still connected to the Pioneer SC-27 via HDMI. As soon as I removed the Motorola's HDMI cable from the receiver, pure silence!
So how do I fix this? Ferrite rings on HDMI? I can't just leave the Shaw STB disconnected all the time! Is it a property of the Motorola versus the Pace, or a property of Cable TV?