Argyro, I am using BMC gear. They have no preamp or line stage. Their DAC1 PRE has an optional line stage module that allows analog input. I have this option. In fact presently I am using a Weiss Dac202 driven by my Macintosh computer into one of the two RCA inputs. I am soon going to use balanced cables from the Weiss to hear whether balanced improves performance.
If you have no need to have analog, I cannot, you can buy the DAC1 without the preamp module. The DAC1 provides control of volume to the BMC amps as well as the "current injection" circuit in running the amps.