I came upon the article by the navguy and almost instantly ordered a kit. I was amazed at the sound of the kit, so later I ordered one O2+dac. I am an electronic technician, so I have assembled and purchased many headphone amplifiers and after testing many I am convinced that this O2, the concept of Navguy, is one of the best amplifiers in the market. You can also try the Cmoybb to hear a good bass and the clear sound will amaze you. I recommend these products to everyone. Period.