How much does a DAC do the more expensive it is?

@thyname wrote, "The specs on the op-amps are fabulous and digital engineers are inherently seduced by the beauty of the math story. There are minor differences in the sound quality between various op-amps, but it's kind of like the difference between a Duncan-Heinz cake mix and a Betty Crocker cake mix."

What then of DACs that don't even have op-amps like say a Denafrips Ares II 12th Anniversary edition?  Is that "better" than using op-amps in some way? What are the tradeoffs? It is a "softer" sound, perhaps not as dynamic?

You said most DACs are sigma-delta.  Maybe so. There's some at every price point.  But are the qualities most of the YouTube reviewers mention about R2R DACs (their "natural tonality and deep and wide soundstage" which have been repeated ad nausem) artifacts of that architecture or "real"?  Did the recording engineer and mastering engineer hear the playback that way, assuming they are using high quality sigma-delta DACs and not R2R ones?

Power supplies obviously play a huge role in how "black" the background can be, but I want to note that linear power supplies might not always be king. Analog Devices and others are working hard on developing switch mode power supplies that should compete well with linear power supplies. They are targeting the medical device field currently, but you can be sure these will eventually find their way into audio gear (or we can hope). 

Just as "some" audiophiles are ready to adopt Class-D amps, no doubt, some will eventually adopt well designed switch mode power supplies and call it a day.

Thanks.  

An obvious observation but I'll make it anyway:  In general, a more expensive DAC should be constructed better, inside and out, and in theory should last longer than less expensive ones.  Say compare the internal parts quality of one of the numerous S.M.S.L. DACs in the <$1000 range with those by Gustard, Audio Research, Holo May, and others.  Those chosen components from the PCB material to the various resistors, capacitors, inductors, transformers, how well isolation is done, thickness of the chassis, etc., all add up to a device that should still be kicking 10 to 20 years from now instead of dying after 3 to 5. 

Does that matter to you?  To some who change gear often maybe not, but to others assembling a system to last them many years, it can. 

Many would like to buy a DAC and not be thinking of replacing it after one year. They'd rather upgrade say another component or feed one of their other hobbies. 

A long time ago, the rule of thumb was to spend 50% of your budget on speakers and 50% on the electronics.  Is that rule still valid or not? In today's "digital world" is it more like 66% on electronics, 33% on speakers and 1% for accessories?