I have used it with the older E7 and it sounds very good, far better than headphone outs despite the "amp not necessary" reputation of the 558s. I am sure the E7K will be as good if not better. For the price it can't be beaten. For non-portable applications I have switched to the Aube T1 which is a quantum leap in quality (and has the flexibility of tube sound as well. When I am traveling I still use the old reliable E7.
thanks for your reply, by the way it's Aune right?
sorry I'm new to this DAC/amp category, if I may know, what makes the T1 better than E7?