Adding DAC to 5-Disc changer

Hello to all-I am considering trying out a DAC for the digital output of my Denon-DVM 4800 which is utelized for all music & HT DVD viewing-does anyone have thoughts &/or suggestions as to where/how to start looking for possible candidates?...how to review & filter out:good..better..best,
are there specifications I should keep in mind for priorities...certain name brands...DAC processors that have reputations as great performers?-Thank You in advance!