I've heard the Vitus RI-100 integrated a couple of times. The reference series shares the Vitus house sound which is warm, textured, yet relaxed and natural at the same time. Build quality and engineering of course are excellent and built around modular architecture like the Signature series. Btw Vitus said the linestage in the RD-100 is atleast 20% better than the linestage in the RI-100.
My Dealer had this to say about the RD-100 "The Vitus Audio modular topology means that its products are future-proof, because they can always be upgraded to the latest technology, but the RD-100 is not your ordinary DAC because it features both true analogue inputs and outputs and a volume control, so it can also function as a high-end pre-amp in addition to a state-of-the-art DAC."
Here is a link to the Stereo Times review of the RD-100 & new RS-100 stereo amp fyi - http://www.stereotimes.com/post/vitus-audio-rd100-dac-and-rs100-stereo-amplifier
My Dealer had this to say about the RD-100 "The Vitus Audio modular topology means that its products are future-proof, because they can always be upgraded to the latest technology, but the RD-100 is not your ordinary DAC because it features both true analogue inputs and outputs and a volume control, so it can also function as a high-end pre-amp in addition to a state-of-the-art DAC."
Here is a link to the Stereo Times review of the RD-100 & new RS-100 stereo amp fyi - http://www.stereotimes.com/post/vitus-audio-rd100-dac-and-rs100-stereo-amplifier