Differences between models of expensive vs inexpensive DACs

For those who have tried many different DACs from very inexpensive to very expensive, do you find that the lower end DACs all sound similar in the same less than optimal way, or is it that the more expensive DACs all sound more similar in the correct way? In other words, are the better DACs starting to converge on the same good sound, or are they actually diverging more in their sonic presentation?  In recent times I've only worked with relatively inexpensive DACs and those all sound the same to me.