The new processors can decode many more formats -- if you increase the number of channels in your home theater that can have a much more immersive feeling -- http://www.homecinemachoice.com/news/art...io-review/13896

The other less obvious side effect is that the new pre-pros also use higher precision DSPs and lower crosstalk / noise floor circuitry to handle the increased bandwidth of the new formats which generally translates into an improved clarity even for the old formats. Depending on how quiet your listening area is and how carefully you've setup your existing system this may be subtle or very noticeable, it is not really just a function of the new pre-pro but even things as basic as how quietly you can tolerate your audio playback before it overcomes the sounds of your HVAC system and other appliances -- one time I helped a friend spec out a pretty basic home theater and it sounded pretty nice for not very much money but then he (or his wife or somebody) decided it would be convenient to have a fridge in the same room and I tell you that old compressor meant you need to up the volume about 20% and to drown out that thing. The psychological effect was that the quietest scenes had the actors screaming at your to "cover up" the fridge sounds...