I have an excellent DAC at a much lower cost that is dual ES9038Q2M with Amanero USB Card etc. and this chip was released in 2020. Some people rave about AKM chips, but such is the price performance now, that with patience doing a comparison will not exactly be requiring much of a raid on the piggy bank should I wish to. I'm sure all the arguments here apply where it comes to the latest sabre vs AKM - pointless comparisons they are all so perfect in terms of performance. Perceptual bias probably involved in one over the other.
In fact we are seeing 'dual chip' devices appearing where switching to sabre or AKM becomes like a filter... I've never had much truck with filters... just provide one that works.
However engineering wise, this R2R implementation seems to be at the higher end of things (quality of engineering wise for R2R). And, if I take some of the other features, quality of the unit, power supply, PEQ facility, the selection of this over a Sabre version for example, just gets slotted into "interesting" for me. Fun. Hobby etc. I might have fun with this regardless, alongside my other.
Your analysis of the actual electronics involved - how it works etc. V. interesting. I had no idea.