Bargain Basement, Giant Killing DACs for PC Audio

As I continue to upgrade my PC based systems, I am fascinated to see how certain DACs somehow retain considerable value for many years.

Because one might think that DACs are more vulnerable to depreciation and obscelesence than say, speakers or amplifiers.

Since this digital landscape changes quickly, perhaps this thread might become popular for a quick update on the latest, GIANT KILLER DACs.

New or used?

USB DACs or depreciated classic and a SPDIF adapter?

Thanks for your ideas.