I had a pair of Krk rockit 8's hooked up to my i phone via 3.5mm to Rca's. I was, therefore, using the dac in my i phone... this was NOT what I would any longer consider to be good sound. Bass and high treble are accentuated and there wasn't much inner detail or quality midrange.
I always wanted to try using them with a quality dac and xlr's... I imagine that would improve the sound by a good margin.
I've looked and looked for a good quality, self powered set up for awhile. I always come to the conclusion that I personally can find a better sounding setup via separate amp and speakers for the $, and there is more tun-ability this way.
However, brands to check out are Audioengine, krk, Adam, emotiva, genelec, mackie, dynaudio (xeo's sound really good), focal (solo 6 BE).