DAC general question

So...yes and no.  There are only a few chip makers.  Some do use resistor ladders and FPGA chips which in essence are customizable chips.  But you are right.  In the end, the design, implementation along with part quality is what really matters.

I agree! Circuit design is the key factor. In fact this can be done inexpensively. Witness the Khadas KTB DAC for $99! Yes it requires a case - but sonically competitive with four-figure DACs! For those not into DIY Khadas has the Tone Pro DAC for $199 - with even more features!

ibmjunkman

As I understand it the actual DA function is done by a single chip ... Am I wrong?

Yes. It's quite common for DACs use multiple chips, such as in balanced configurations. And as @verdantaudio noted, some use FPGA chips, which are essentially custom chips.

input stage
clocking
d/a conversion (chip, fpga, or r2r ladder)
power supply (linear, switch mode, separate/combined for various stages needing power)
output stage (ic, tube, transformer, ss discrete...)
isolation (physical and electrical)

it all matters in determining what a dac sounds like

It’s all important, but from what I’ve heard from other hi-fi enthusiasts much more knowledgeable than I (and judging with my own ears, which may not be as keen as others’) it is the quality of the power supply and the type and quality of the output stage that make the most noticeable difference in a DAC’s sonic character, given that the clocking and conversion are above a certain standard of performance. Again, I’m sure others will disagree, but that’s been my experience.