I have a new Onkyo TX-SR703 AVR and I picked up an XM Connect and Play antenna and activated service, since the 703 is XM-ready. I noticed, when listening to different inputs (DVD, iPod, CD, etc.) that I heard a faint, but audible high-pitched "hum" sound. Usually, the sound is most noticeable during quiet songs or parts of movies - I definitely hear it coming from all inputs when nothing is playing. After some troubleshooting, I discovered that the sound went away when I unplugged the XM Connect and Play antenna! Anyone have similar experiences? I don't know if the problem is with the antenna or the Onkyo 703. If I need to exchange one of them, I don't know which one to take back.