DCS Ring dac converters are also similar to the newer top level stuff from Burr Brown and Analog Devices, being hybrid, which are part R2R and part DS, (Delta Sigma, 1bit, Single Bit, ESS, Bitstream) or whatever other pseudo names DS has.
Burr Brown/ Texas Instruments, Analog Devices now are doing "hybrids" with their better d/a converters, 4 or so bits of R2R and the rest DS. This makes them more expensive to make than DS but said to sound better, yet still no where near as expensive to make as full R2R was, the reason R2R was dropped in the first place and 1 bit DS (delta sigma) took over, because it was very much cheaper to manufacturer than R2R.
But things seem to be going full circle again and R2R is being shown for what it is, bit perfect for converting PCM, where DS is just a facsimile.
And many Dac makers are now doing full R2R again in "discrete form", and the results of the good ones are better than the last of the great full R2R converter chips from AD Texas/Burr Brown ect ect
Cheers George