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

In case you're getting the wrong idea, I don't firmly correlate money with quality. Never have, really, for audio components. Case in point; I've loaned out my Herron VTPH-2A phono stage to a friend and have substituted into my system my almost forgotten Schiit Mani. 

I mean, yes, there is a difference in presence and space, but that little sub-$200 solid state is absolutely incredible. 

If only price were a good guide. There are many DACs that will trounce your DAC, and some may cost less, I don't know about that end, but it certainly would be possible. The problem is that we have limited exposure and we don't all agree as to what we consider diminishing returns, not to mention what we precieve as sounding good. There are a lot of DACs that can better the Gungnir easily. The problem is that when someone recommends x, you don't know their taste in sound, the strengths and weaknesses of their system, etc. This renders their opinion as virtually useless to me. I have more often been disappointed in highly rated equipment than I have been pleased with it. It doesn't matter what magazine the review is in, though through the years I have found several reviewers who have high standards, and with whom I usually agree. Even if stereo shops abounded, paring this with that could negatively impact our impressions of a certain piece of equipment. This is a very difficult hobby to get to a point of contentment in. 

The DAC is important, however improving the streamer/source I think is just as important. I have owned a few DACs and they all sounded different but all were improved when supplied with a better digital supply.

I'm going to dust off my Ayre Codex this weekend and compare it with my PS Audio DS DAC.  Both will be fed by an iFi Neo Streamer due to it's fiber optic input and aftermarket LPS.  I²S out to the DS DAC and USB to the Codex.  I suspect they'll sound closer to one another than their cost difference suggests. 

and then there's this, too: a central component like a new Technics integrated, say the su-r1000 if you have the cash, or an Accuphase with the dac module, and don't add more "stuff" to your chain.  The Marantz Ruby sacd player / dac unit also sports fine dacs, and thus does double duty, if your amp is analogue.

but, I know people on this forum have fun playing around with "separates" ... but dac diminishing returns is hard and real.  usually "better" is really just "different"... and even then the differences are usually subtle.  

swapping out dacs can lead one on an endless rabbit hole with no final bottom, but again I acknowledge that's technophile fun and fine as long as it doesn't detract from a musicphile goal of enjoyment of music (if one is actually a musicphile, and if not well then have at the tech chase and enjoy the trip).