Just got this a month ago.  Right out the box, the sound had that "WOW" factor.  It is detailed and crisp.  With HiFlight's topkit, it even open up more and had more "WOW" into it.  This morning while taking my train commute listening to Kenny Burrell with my ipod classic and a Ray Samuels LOD...

My first portable amp and I am very impressed with the difference.  Using a DT770 32, Grado SR80, and Senn PX200.  I am not an audiophile as I am not fluent with specs.  Just use my ear to gauge. As a kid, enjoyed my father's sound system. He is a tube guy. I am sure that there will be better...