Very first thoughts ( 2 hours of travelling through my music ) : My HD800 sounds smooooootas butter but clear and I feel a serious improvement in soundstage ( deeper , more layered with something more real. I was a bit afraid of what what I read here or there about the Sonett. i was afraid to have bought a more expensive Vali i really didn't like. I was definitely wrong. The DNA sound smooth and the Metrum/DNA Sonett Combo gives my HD800 a great overall tone. both meaty and creamy and it seems that some music I didn't really enjoy previously sounds now amazingly with the new combo.
Everyone should take what I say with a big grain of salt. New toy effect , Honeymoon , personal bias can strongly affect my opinion
Fortunately the blue color don't bother me. I like the fact that Daniel likes that his gear has a very distinctive appearance