I wouldn't entirely agree about its subjectiveness. Its true to a point, but there are also some very "real" stats to check out when choosing a DAC. THD, SnR, etc. You compare a laptops built in DAC to a Mytek Stereo96, or Lavry unit, and its night and day. Of course, monitors, etc are also going to have a huge impact, but a DAC is quite important.
But yeah, the DACs in a single price range are usually similar, until you bump up to the next price point. You have your laptop jacks, ipods, etc. Those are dimeadozen cost-cutting dacs. Then you have prosumer interface market dacs. For the most part, they are going to sound a lot better than a laptop or something. These units are usually a $150 to $1500, and are all likely going to sound fairly similar. Then, you have your mastering grade, top notch DACs. Mytek, Lavry, Prism, MH, Crane Song, etc. The jump in sound quality is not as drastic as the jump from laptops to an interface, and for 99% of people, definitely not worth the money. However, when I A/B my profire interfaces to my Avocet or ULN-8s DAC, there is a noticably improvement in sound quality. You mainly hear it in the highs and transients. The spacial imaging and stereo field is much more defined as well.
New Recording Setup: iMac 2011/ULN8/Profire 2626/Axiom61Pro
Experience with the following M-Audio products: Profire series/Projectmix IO/Firewire Family series(410, 1814, etc)/Axiom series/Axiom Pro series/Oxygen series/Fast Track series/+more