I am looking to upgrade my HT receiver. I currently have a Kenwood 1080VR 5.1 DD receiver. I want to explore both the receiver route and the seperates route but I'm not sure I understand exactly what a pre-pro is or is not. I understand that a receiver has an amp built into it and I believe the pre-pro requires an external amp(s). What else does a receiver have that the pre-pro does not? What are the basic differences in upgradeability between a pre-pro and a receiver? I am mainly interested in movies and would use the unit little if any for music. Is one better suited for movies over the other? Thanks in advance for any help!