I have been experiencing this for a few weeks now. It's particularly noticible on the main and Scottish news and Pointless. Other times and other stations are fine. I thought it was a BBC thing but it's only on here that others seem to be writing about it which does suggest it's a Virgin issue.
I first thought it was the TV or pottery vase near the TV that was buzzing at certain sound frequencies. I have now ruled that out as I have the option with my TV sound to pass it optically through my hifi to two external speakers. I've done this with the TV volume at zero and the distortion is still the same so this rules out the TV set. Removing nearby glassware and ceramics doesnt make no difference so I'm pretty sure now that the distortion is in the broadcast signal. We have also sometimes expereinced pixelation of the video signal. What's going on Virgin?
PS Ive tried rebooting ther V6 box but that made no difference