DAC general question


As I understand it the actual DA function is done by a single chip. If true do all these DAC makers use custom chips or are there limited manufacturers of the chips? If so then the goodness or badness of a DAC is dependent on the circuitry around the chip.

Am I wrong?
128x128ibmjunkman
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Ladder dacs are very popular now, so companies are making them.  Nothing wrong with that, but remember some of the best sounding dacs ever made used "off the shelf" chips.  The older top-line Esoterics used AKM, as did APL.  I believe Audio Note dacs use chips and the reviewers can't stop raving. Personally, I would buy what sounds good to you and forget about the design, unless it bugs you to the point where you can't enjoy it. 
As a side bar, you can purchase an inexpensive DAC that will "measure" extremely well on scientific equipment, but will not sound as nice as expected in a quality system.  This can cause a real reaction from the objective only crowd but it is true, thus the preference of many for the R2R Dacs. .00000000x distortion will not equate to a great sound depending on the rest of your components.  If it was only about a chip and measurements, we would all be buying the 800 dollar Chinese DACS that have a SINAD of 118+.   I agree with @mastering92

I agree with  jjss49.  I would only add that the quality of components can also make a difference.