Ah, I think I've got it. No, I obviously didn't do as you said, sorry!
I can see how that would work! Sorry to 'hassle' you, but presumably, I could then get an audio splitter which would allow me to connect both the bt vision and PS3 simultaniously to the DVI so I don't have to physically get up to change from one audio input to the other? Or would that not be possible because of the setup of my tv?
I'm off to Maplin now!!
Thanks so much, you were much more helpful than the guy in the shop!