Generally speaking, a good 2 channel amp will surpass a home theater receiver. That is *IF* you can hear the difference, *IF* you have a room layout that can let you set up speakers for best placement, and *IF* you want a new toy to play with.
If you are happy with what you have, and it works for you, and you don't feel like opening up a can of worms, you may be better off with what you have. Denon makes nice receivers.
Don't get hung up on "its old it must sound better". That is not always the case.