Same problem here. Random sound dropouts. I could be watching something with no problems and when I change channel no sound on that channel seems to mainly affect non HD channels. The only way to fix is to turn off the box and on again or the tv. Frustrating!
I've had my Virgin V6 box for only a few weeks now and I've immediately noticed the audio dropout issue, also referred to on these forums as the Dolby Digital issue. I will experience very short audio drop-outs at irregular frequency, usually when watching recorded playback. Most notable has been when watching my favourite programme at the moment - Blue Planet 2 recorded from BBC 1 HD (channel 108).
I have the V6 box connected directly to my Samsung UE48JS8500 TV via a high speed HDMI cable. The TV outputs audio via optical cable to my Sony HTAS5 5.1 surround system. The V6 box is set to output Dolby Digital as advised in the set up guide.
This is extremely disruptive when it happens - very jarring to any program and not just the sort of thing that only an audio/videophile would notice. I am really disappointed to see that looking across these forums this issue is so well known (with it's own ticket number) and goes back such a long period of time with no real promise of resolution.
I would like my dissatisfaction registered to my account and for someone to contact me regards credit options for this well-known issue.
Doesn't matter anymore. Decided to end TV package as my discount was coming to an end. Just sticking with BB now as most of my viewing is from the Freeview channels and Virgin weren't really offering me anything worthy to stay with them.