I am a believer in high-end DAC's. I was convinced to throw down some serious cash on an MSB Analog DAC with fancy power supply and volume control (as equipped, $12K+, new), which replaced my preamp as well (Plinius 12P). I think that it was a good improvement over my already good DAC/streamer Naim NDX. But as everything in audio, how big an improvement is dependent on so many factors, such as speakers, room, amplification, power, cabling, etc. Highly revealing speakers will show more differences than rolled off "warm" ones, etc. That's the irony of audio, I suppose. The more expensive your components are, the more expensive they need to be to sound good. So are DAC's overpriced? It depends on your system. a $90K DAC in a $20K system . .. probably not a great match. Then there is the unique language of reviewers:
"noticeably more presence" = 5% better
"makes you feel right there" = 5% better
"a big difference over my reference" = 10% better
"Blows away my reference ___" = 10-15% better
"to my ears, the most amazing ___ since the invention of the transistor" = 15% better.
A little off-topic, but just once I'd like to read an Absolute Sound or Stereophile review that instead of gushing superlatives says "this piece of equipment costs $20K and sounds no better than a $3000 one. Buy it if you want, and it sounds good, but its just not worth the money."