Seriously!!! Are there any mods out there that could give us an update on this? It will keep being bumped up until we get an answer. I have noticed other people starting new threads about this issue, so there are lots of people with the same problem.
Just had 2 V6 boxes installed today. Plugged into the TV with sound output via hdmi arc to Sony surround system. Volume at 65/100 for normal viewing, very quiet, 100/100 is loud-ish, room filling but not movie night loud befitting a system with sub that we can normally do. It's definitely quiet, much quieter than the v+ boxes we had and much quieter than other sources. Tried all the sound settings combination on V6, TV and surround to no avail. Multiple hdmi leads too, but frankly that's just lip service on a digital signal.
It's typical of VM's customer service. They will eventually acknowledge a fault exists but that's usually as far as it goes. We're paying top $$$ for this every month and I've had 2 V6 boxes now for about 2 years. I've decided that the grass is greener and will be going back to Sky at the end of my present contract.