The Producer of the RH Design, is not just your average DIYer.
There are all aspects of HiFi devices produce by their hands.
DAC's, Head Amp's, Phonostages, Pre Amp's, Power Amp's and quite few Speaker Builds, and over the recent year+ a Tonearm is also produced.
A DAC built for approx' £200 recently A/B compared to a Denafrips Venus really caused the Venus owner to rethink their situation with DAC. It seems the recent Denafrips Firmware Updates has allowed the DAC owner a little more grace, as they feel there is improvement now on offer.
I think is fair to say the RH Design is buildable, but the fine tuning of the finished product is probably best left to those with a time served experience.