Oak,

So, how old is the CD changer you are currently using? Unless it is so old that a very primitive oversampling circuit is used, you might not hear any improvement from a brand new unit. The CD technology has been mature for a good while now, so that the actual bottleneck for sound quality is in the media format itself, not in the playback hardware.

Also, I would say that today's DVD players produce basically identical sound to a dedicated "high-end" CD player, even if you use the onboard DAC in the player. Of course, as chess said, it is identical, period, if you digitally connect it to your receiver/amp.