I don't have much to compare it against especially for headphones or as a preamp.  I have used my Beyerdynamic DT860 headphones on my PC for a while and talked into getting a tube amp from a guy at my work.  I thought I would try something cheap to get the idea of what a tube does to music.  This one seemed decent and the other models had good reviews so I liked the idea of a EQ and purchased this one.    At first when I unplugged my headphones from my PC (Motherboard Sound card unfortunately, hope to be getting something more shortly) and the...

I used this with my Beyerdynamic 860 and Ultimate Ears TripleFi 10.  It works and does a great job for most music giving it a more full range of sound.  I have tried it in my PC headphone out and mainly with my T989 Samsung Galaxy S2 as well as on an iPhone.  Depending on the quality and type of music you will want to use EQ2, EQ3 or no EQ.  EQ1 is a joke but the others have given much to the range of sound any device puts out not to mention it makes it significantly louder.  For $25 I cannot complain, doesn't do as well as when I listen through my...