When you say, "if you are trying to compare architecture of dacs (R2R, Sigma-delta or Fpga) and bring some conclusions out of it, yet alone trying to conclude something on bases which model of chip is in some dac." you seem to miss the point completely, or at least my point.
The "architecture" of any DAC has less to do with the chip (whether it be S-D or R2R or FPGA) or discrete R2R and more to do with power supply, clocks and analog section. That’s how one can begin to judge a DAC, yes, even before listening. Doesn’t anyone ever look inside one of these? Perhaps I’ve spent too much time over at head-fi.😊
Using the Esoteric D07-X as an example, some may think it’s a good DAC because it costs about $5000. But Japanese made DACs are priced (or overpriced) like US or European DACs. If you look inside the DAC it has a single relatively inexpensive, and unshielded, r-core transformer supplying both digital and analog functions, a single clock and, as far as I can tell from on-line descriptions, OP amps controlling the analog section.
That doesn’t spell high quality in my dictionary--no matter what the chip is. The chip, given something respectable, is not all that important. IMO it has been made important by marketing. It is what they want us looking for, along with a fancy case--rather than the stuff on the inside that really costs and really matters.

