Many thanks for your reply Jeff, I have looked at the link with interest.

I don't need to be able to get sound from the system for radio/cd when viewing the AV channel as I am having a custom stereo instsalled that completely bypasses the nav unit which is only going to be used for the sat/nav visuals & instructions and TV sound comming from a new single speaker install.

As I am doing this and most of my budget has been spent on the stereo upgrade is there a cheaper / simpler way as suggested in my original post?

If not and I have to go down the route you suggested, would there be any compatability issues as I aquiring a TV signal in the UK and not USA?

Regards,

Paul.