Occasionally, when changing from a HD channel to a SD channel by either 'Last' or selecting from guide, loose sound on all channels. Only happened since installation of new Tivo box. Only connections via HDMI direct between TV & TIVO, swapped TV inputs from HDMI2 & HDMI1 but still happening even after new HDMI cable installed by Virgin on call out.
Sorry to hear this is happening and I would like to welcome you to the community.
What I would like to do is send one of the team out to take a look at this for you so if you click on the purple envelope at the top right of the screen you will see a message waiting for you with further information.