Among other aspect what high-end system are able to show in DACs is their space reproduction and background information capabilities which are can be lost by lesser quality DACs. This information adds so much to feeling being there, the last ounces of reverb down to venue at which the music was played or due to construction of the instrument or ambient in general. It is what is between the instruments the low-level detail retrieval is what a true resolution is which can be drawn in the noise floor of the DAC but most often of the system in general. A true high-end DAC will be able to get all this information beautifully laid down in front of you in 3D space in a very musical way and without thinning of the sound which is so often mistaken for resolution and in 99% of times leads to brightness which high end systems will quickly highlight as most times they are very truthful and neutral magnification glass type of the deal which if fed garbage will return magnified garbage.
Or another way of looking at it...
What a high-end DAC will do is take all the information recorded in a digital file and convert it to an analog signal without introducing distortion, noise or jitter.
Lately, literally really only the last 12-24 months, it has started to become possible to get a DAC that can do this where any noise, distortion or jitter is 20dB below the threshold of human hearing. And to get this for low prices. We have recently reached the point where price is no longer a good guide to quality.
If the information in the file that can translate to space, clarity and soundstage is not recorded in the source file then the DAC should not try to inject it, for files that do have such information would then have too much.
You don't want your equipment to apply blanket filters or distortion to every recording for they will degrade more music than they will enhance and those few recordings that are enhanced will only be at random. Adding such information is better done with specialist digital software and applied either algorithmically or tuned by ear on a per-recording basis. Of course this is best done in the studio, but 3D or surround filters and suchlike can be added to taste after the fact.
There are still a lot of DACs out there that are not of high quality, but soon (hopefully) they will be driven out of the market.
I think the next link in the chain to see this same progress are Class D amplifiers. ICE, Hypex and Purifi have now released modules which are being included in higher end equipment from the main audio brands which take an input signal and amplify it without introducing audible noise or distortion. As with DACs an amplifier that does introduce such distortion, whether simple or complex is applying a blanket filter or distortion to ALL your music, regardless of whether it is appropriate to your source material or not.
I think it likely that perhaps we will start to see more complex DSP software aimed at the end consumer making its way into the consumer space, as the DAC and amp elements of the chain emerge as essentially being "solved" problems.
In hifi of course this is most obvious now in room correction. We are certainly seeing this trend in wireless headphones at the moment in recent releases from Sony, Apple, etc. and it is usually combined with noise cancellation.