Actually I have heard them. I had the Lamm L2 in my system and even though I own Lamm L 2.1's and figured that there would be an obvious synergy the preamp was cold, dark and sterile. The Ref 3 eclipsed it by miles.
One of my closest friends owns the Callisto in an all Aesthetix system with dual power supplies and a Sirius 3 TT. It is excellent but he told me that he prefers my Ref 3 better.
I briefly heard the Kondo and felt it to be only just OK.
As far as posting absolutes, those comments came not from me but rather from an owner of an extremely high end manufacturer who has had opportunity to listen to every SOTA preamp out there.
I will reiterate, that until you hear the Ref 3, you haven't done your system justice. I must admit that I was dying to own the L2 and it couldn't come close to the Ref3 in my system. Bear in mind it is all about flavors. I prefer the sonic signature of the Ref3. I also owned a Ref 2 Mk ll as well and thoroughly enjoyed it as well.