andytucker:
Its strange cus i never really knew how to get DTS sound on my receiver until i did some searching on the net and came up with i should use my movie button to get DTS sound which i must admit sounded much better whilst playing the U2 Live DVD
Ok, listen carefully, you'll only get the full 5.1 channel DTS sound if what you're watching has a DTS soundtrack on it. Now it's entirely possible that the U2 DVD does have a DTS soundtrack, music DVDs do tend to because, arguably, DTS sounds better than Dolby Digital. This does rather presume that you're connecting your DVD player to your receiver using a Digital connection, and not analogue stereo connections.
Assuming the DVD does have a DTS soundtrack on it and that you've actually selected this soundtrack from the film's menu (DVDs rarely, if ever, default to DVD, they usually default to Dolby Digital), you're better off leaving all the other buttons on your amp alone, just let it get on with with the standard soundtrack, you only need Pro-Logic(II(x)) or Neo:6 when you're listening to stereo sources, otherwise it's just mucking up the careful mix that the film makers have laboured long and hard over.
As for your Sky box, again, assuming you've connected it to your amp with a digital connection, just leave the Amp in Auto Format Decode and it'll switch modes along with whatever the Sky box is outputting. I was watching the Star Trek movies on Saturday from Sky Movies, The Motion Picture was broadcast in Pro-Logic and my (Sony) amp played it as such, then the Wrath of Khan started, which was broadcast in Dolby Digital 5.1 and lo and behold the pretty blue light came on and the amp started playing in full 5.1, easy as that!
Did I mention using digital connections from your DVD player/Sky box to the amp? Yes I did, twice, because it's important, if you aren't using digital connections forget everything I just wrote because you'll never get "proper" DTS (or indeed Dolby Digital).
Apologies if this all sounds patronising but you sound like you're starting from the beginning so I'm trying to be as clear as I can.