The simplest answer is there would be no benefit to using a dedicated C.D player.
1) More components, more room, more money. This task can be done competently by your Blu-ray player.
2) If you use a digital connection such as a coax or optical(toslink) cable the digital to analog conversion will occur in the same place-your receiver. Even if you use a analog connection and take advantage of a so called "superior" DAC of a dedicated C.D player the differences in sound quality will not be night and day, certainly not worth the extra cost.
