Just received mine today. Haven't gotten the chance for extensive listening yet but I am very impressed already. Have never experience such full-bodied music on my HD650 & Fidelio X2 until now! I didn't do the optional 1 Ohm modification but I'll say that my X2 sounds amazing, just the way I wanted. So much for the theories. Thank you CEntrance and Massdrop!
BK245Mine is still on the way. I will use it with HD650 as well. I am not sure how much dacmini will improve the music, and now I am still using HD650 with iphone or laptop but I am not satisfied with the sound.