How easily can you distinguish between different DACs?

The technology behind DAC is way more advanced than it was 10 years ago. You can get a DAC with a 120 dB signal to noise ratio no larger than a thumb drive. It is at the point were all dacs operating at the same rates do exactly the same thing, accurately crunch number. Any sonic difference is in the analog section and all sorts of Tomfoolery can be done there to produce a "house" sound. Personally, I do not want the house sound. I want THE sound without any pontification. 

@invalid

The best way to determine the ability of the digital portion of a DAC is the signal to noise ratio. I would go with whatever DAC had the most neutral analog section be it discreet or an op amp. There are some pretty wild chips out there today and the only thing discreet will do for sure is cost you more. 

Because I require more DAC channels than most two channel people I go for digital preamps that have the DACs built in. I require 6 Dac channels. The unit that I will have shortly has 8 DAC channels built in along with room and speaker control, bass management and high resolution digital EQ. I digitize my phono stage.