Both modules has pluses and minuses, personally I have opted for ESS 9018.
Smoother and softer sound, more natural tone and very easy on the ear character are some very strong pluses, that are obvious from stock module. Who thinks Conductor in stock form has a slightly digital sounds to it, I recommend the SL 1793 module. Who doesn’t own a Conductor, but wants a richer tonality then I think Conductor SL1793 would be a good choice.
Full Review Here: http://soundnews.ro/2013/10/06/burson-1793-dac-pcb-english-version/