In my honest opinion . I owned the Ref 5 se for about 2 and a half weeks and the demoed the 6. Lets just say that i put my 5 se up for sale right away and bought a brand new 6. The 5 se is a very good sounding preamp, the 6 is like that but WAY more in every way you can think of the 5 se. It is so good i didnt want a used one. I wanted a brand new one from ARC. To me it was well worth the extra thousands. I love this 6 so much that for a single chasis preamp it will stay with me for a very very long time. And yes i totally agree that it a totally different preamp than the 5se. It is not even an upgrade to me but a totally different preamp.