There might not be anything wrong with the one that comes with the Dr.Dac2.
Usually regulated > unregulated, linear > switching, and noise-filtered > not noise-filtered. But the amp/dac itself probably has its own noise filters and voltage regulators if the stock power supply does not.
im new abpout that kind of stuff but the marks are as above
i haven't heard different configuration but this one is my personal hero - it blew me away. i have westone 3 and akg k701 but hd600 is the best for me here. it is soft gentle sounding for me with HUUUUUGE soundstage....i can hear it perfectly when it comes to series like Californication or Dexter - reasonably new serials which sound BIG on my gear. as for the w3.....i couldn't believe that they can be more punchy but aye...they are . The source is DYIMod made by Qusp, plugged into line in via Qusps LOD + female mini jack to rca connects. that is all i can write ATM about it because i am still testing it. i'm sure that i'll have dr.dac2 for me too, when the time will come to give it back to my mate.