streamer to DAC connection


streamer to DAC connection:  optical, USB or COAX best?
128x128jw944ts
for what it is worth to those on this tread, I am now aware there are some articles about this subject, but interestingly, neither my DAC or cable manufacturer recognize this as an issue.....I would certainly think they would if it was a significant issue, as it would cause consternation about their products and the resulting sound....
USB best.  No documentation to prove it.  Just lots of testing. And if you want to listen to DSD, which is to be recommended as it sounds better if a genuine DSD recording (ie not simply upsampled) then you need USB. 
OP. I'm with you on this one. Nothing wrong with a question to learn. Some people are extremely touchy and sensitive. The proof is in the pudding, and that is, how does it sound???  :-)))