So I'm not sure about putting this up against Dostoevsky or some of the beautiful writing of Nabokov for instance, but there's a chapter towards the end of The Peripheral by William Gibson that I've always respected which is just a conversation between two characters - but what I love is that it's direct dialogue (between speech marks, line by line) but with no need for indicators of who is speaking (e.g. X said... Y replied). He doesn't even introduce who is talking. You just get the dialogue alone.

It's just not necessary by that point to say who it is because he's developed the voices of the two characters so well that you instantly know, and the context is clear too.

I just always felt that it was evidence of a writer who had made the effort to make distinct characters with clear voices - you had really got to know these people. A bit of a writerly flex too I guess.