I currently have a Digitheatre DTS which has gone wrong - I've had it for about three years so it is out of guarantee. Just wondered if I upgraded to a separate amp/decoder if I could still use the speakers? I don't have enough to replace everything at the moment. If I did this would the sound still improve or be as good as the Digitheatre? Also, I have about £200 to spend - what would be a good amp to buy? Thanks.