Just because a DVD (or CD) player has a 24/96 DAC does not mean it sounds better. There are Chevy's with 16 value 4 cylinder engines, but that does not mean they perform like a BMW or Mercedes with the same basic engine configuration. It is the quality of what surrounds the DAC chip that makes it perform. All things being equal, 24/96 is an improvement over what came before. Your Denon DVD is a typical mass market player, so all things are not equal. The Luxman (or any older high-end player) would most likely sound better. Not to scare you, but that Denon model has a terrible reliability record and will not play some DVD discs. I would replace it.
If you're doing demo's at a dealer, see if they will let you bring the Luxman in for a comparison, or bring one the the new better players home.
The Cambridge D500 is one of the few under $500 players that can compete with the more expensive ones you mention. There is usually a demo for sale at AudioAdvisor.com for between $329 to $349. New there is $429.