How many of you are using external surround speakers. If not, my solution (I am using an HDMI cable hookup to a Virgin V+HD Box)was to set the audio settings on the Virgin on screen menu to HDMI audio override. This asks me to ensure my external speakers/amp are connected. However, you will still get sound as the surround sound function does a good job of mimicking external surround sound equipment. I noticed that the sound quality improved when I switched the surround function off. I think it is the way the virtual surround feature distributes sound over an HDMI interface causes it to distort and vibrate the panel.
Also, if you want the best picture quality over HDMI.
Turn off the Cinema mode unless using blu- ray.
Turn off the CTR mode
Turn off Digital Noise reduction
In fact turn off any of the gimickry that is intended to improve picture quality. This works only on the built in Digital Freeview. Over HDMI they all worsen the picture and cause artifacts and motion blur/stutter on occasion.
Set the HDMI picture mode to Native. Sure on occasion, such as on Film 4 hd, you'll have to put up with letterbox borders to an extent but I noticed another big picture improvement , when the image wasn't being stretched to fit.
Paul M Murray
August 2010