I had use opa604 in my machine, its good, but I hoped this can be better。 after a lot of reaching work, I get 4 v6 classics first。 its sounds smooth and soft, details still be there。 I like it very much。 Then I wanna know how the vivid should be。so I get another 4 v6 vivid s for my machine。 a little more energy, sound a little younger, faster。 and the details are more clear。 I love them both。 maybe, classic is a little more。。。