dacs are really big diffrents at all ???

hi my friends.
im aowner of LEBEN CS600 AND DEVORE NINES .
im search about 1 years for dac or something really good that will be good combinations with my system .i used pc-q1500 of fujitsu (ion computer) small one but quiet and good i really cant uderstand what about all the big deal around dacs im test few dacs around 500-2000 $ and reall dont know why its worth to buy dac more then 500$ im never hear such abig diffrent and yes i have agood ears and few people hear it with me and they say no diffent at all.
i know all about to set my pc i use foobar2000 and play with kernal streaming and asio .
people hear suggest me the dac of metrum octave nos but i cant hear it and try this in my country .someone in my country sell hegel dac he suggest me the hd2 or hd11 dac .
what people u can say about it ? is it worth ? is it really more good then good soundcard around 300$ ??
any help suggest opnion pls ?