I have to say I was very impressed with this little beauty.  For my 63 yr. young ears after being subjected to some of the most ferocious live hard rock and heavy metal it really does justice to my more subdued audio selections now.  The imaging is quite nice especially listening to live performances and various electronic music like Vangelis.  I especially love to listen to the beauty of the Hammond B3 organ from ELP, Triumvirat, Eloy, Deep Purple, YES..etc.  Nothing like listening to a tube driven keyboard thru a tube amp.
 
One thing that I did immediately "modify" was I raised all four tubes approx 3/4" using 9 pin noval tube socket savers that I picked up from ebay at the following link:
 
http://www.ebay.com/itm/150471555641?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 

Seems to keep the amp running much cooler and actually gives the amp additional visual appeal.
 
Sorry my review is not as "technical" as some others, but if you are looking for a nice "mid-price" setup, the Schiit Valhalla 2 and the Modi 2 Uber make a nice entry level system.  I only have one pair of headphones and those are my Sennheiser HD600's.  As many have said, it seems this is the perfect amp for these 300 ohm cans and possibly the Beyerdynamic DT 880 or 990 250-600 ohm cans.