To preamp or not to preamp?

I am pulling together a two channel system that will also have a home theater function. At this point, I am only going to have one source- a CD/DVD player. I have noticed a few source units (such as the EAD DVDMaster 8000) that are able to connect directly to the amp and eliminate the need for a preamp. I am trying to understand the pros/cons of such a configuration. Does anyone out there have experience running a system without the preamp that they would like to share? System is under construction and so far includes Quad 989s as mains with dynamic Quads to cover the other three channels and a Levinson 334. I am looking to spend less than $4000 for the source unit.