sometimes you will like the DAC inside the preamp and sometimes you may prefer what came inside your CD player.I suppose there are a few components that could be considered preamps that have dac, most do not. CD players have dac's.
I use digital rca to bring the digital (1&2) signal from a transport or digital cable box to a DAC (converts the signal back to analog) to a analog rca to the pre/amp. As far as I know a regular rca ic can not transfer a digital signal.