Opportunity to buy the best Preamp... but which?

I had the AR Ref 3 and the CJ Art 3 and several others but the new Einstein " The Tube" is the most musical of all, hands down. I also have a second system which has Avantgarde Duo's and I use a Meridian 861 pre and just recently added the Meridian 800 cd player after going through about 20 cd combinations over the last 2 years and this was the best combo by far.
I also use my Meridian for a high end Home Theater system as well but when used for 2 channel it is an incredible preamp and I would take it over any of the ones you have mentioned. It is the one piece in my system along with my Duo's that I have never had the urge to replace.

Einstein's "The Tube" preamp is good but ultimately more colored and more difficult to match with a system. It's presentation is forward (ala B&W speakers), soundstaging is OK but not Ref 3 territory, and it's ability to capture the way live music breaths and expands and changes it's dynamic envelope is replaced with a sense of artifice which imbues a presumed quickness...but it misses the beauty that connects all the notes together. A ref 3 needs proper setup and time in a system to be fully appreciated. One must also appreciate exceptional music and have a great reference point (BSO perhaps)! As for Meridian, owned the G6 and demo'd some of the other reference gear. Meridian reminds me of very good Hi Fi, exciting and flashy but missing the soul of a performance (great home theater stuff..if that's your bag). By the way, the ref 3 needs about 500 hours before it shows it's mustard..and it needs a great power cord, the stock one would take it into average land.

Are there any new designs that leapfrog all these top machines?

There are certainly preamps that have technology that do represent breakthroughs. In addition a top preamp will have the best coupling caps available and things like that...

"Are there any new designs that leapfrog all these top machines?"

If you have followed the H-CAT thread and its new technology/ies advertised, corroborated by its owners, there sure are new designs that leapfrogs these top basic design machines at thousands less.

Me, I will stick with one of these top machines though.

while one may have the opportunity to buy the best preamp. the best preamp only exists in one's mind, not in reality.

best is a value judgement, determined by criteria devised by an individual. another individual may devlop a different set of factors. there will always be a disagreement, because priorities differ. it is more relevant to decide what you like rather than so-called quality.