External DAC for two channel with B&K Ref 70

It is my understanding that the B&K Ref 70 does not have analog passthrough. If I used a Musical Fidelity Trivista 21 DAC, with mods, it would still have to go through the Ref 70. Does this mean that any benefit of the Trivista DAC would be lost due to an analog signal being converted to digital, for digital volume control, and then back to analog for output to amp? Secondly, would there be any benefit to using the Trivista DACs digital out to the Ref 70? The digital out must be there for a reason on the Trivista DAC. Overall, it appears what I am considering will not be beneficial. Any advice out there?