I think what Mark is getting at is that Balanced Lines are typically for noise rejection, which is more important for longer runs like you would have with Microphone Cables. For the standard 1m to perhaps 2m, RCA coaxial cable work fine.
Now if you have XLR Balanced lines and you can use them, you might as well. But there is no need to go out of your way to use Balanced Lines unless there is some external circumstance that dictates it. For example, a noise environment or longer than average cable runs.
It would also be helpful to know specifically what equipment we are dealing with, and how long the wire runs are?
If you have a DAC that is better than the DAC inside the CD Player, then there might be some advantage to using that external DAC, and if the external DAC does have XLR output, and your Pre-Amp has XLR Inputs, and you want to use them, you certainly can. There is really no difference between the Balanced lines being built into the CD Player, and the Balanced lines being built into the DAC. Ultimately, the signal comes from some DAC to your amp.
I personally would not buy a DAC just to get Balanced Output. However if you already have the DAC, and you think it might be better than the CD Player internal DAC, certainly use it. And if using it gives you Balanced Lines ...fine... use them too. But I would not personally go to great expense just to use the Balanced inputs on the Pre-Amp.
Keeping in mind that a very vast majority of amps and CD Players use common RCA unbalanced lines and they sound just fine.
So, to make a real determination, we would need a lot more information. But on the broad scale, what you propose should work just fine. The quality of the sound you hear is going to be based on the quality of the DAC you use. And of course, assuming that the CD Player actually has Digital Outputs.
Steve/bluewizard