Audio research ref 6SE vs world

The Reference 6se is excellent.  My go to SS pre when I really want a hard core comparison with tubes is the SST Ambrosia Preamp.  Loaded with features,  it doesn't sound like tubes, yet,  it does have a flare, a tube like quality,  smooth, detailed, excellent soundstage and loaded with world class performance in several features.  
If you like the AR Ref 6SE, I would recommend the SST Ambrosia as a comparison.  Warning, the Ambrosia needs a couple hundred hours of signal passing through it for break in if new and then just leave it on.  Beautiful pre that passes through the source quite honestly.   

Anyone compare Prima luna evo 400 preamp to ref 6se?

Any other preamps people enjoyed more than ref6 or ref6se?

I had the opportunity to spend a few hours listening to the REF6SE in a system with the Vandersteen Kento's and the Vandersteen M5-HPA monoblock amplifiers. For the first time I heard Richard's amps sound as good as the Aesthetix's amps on his speakers. This system, which also included an Ayre QX-5 DAC, made the speakers disappear and performers sound like they were in the room.

I have heard this system before the REF6SE replaced an LS-28 but it never sounded like this. The detail, the musicality and the bass were amazing. And the voices!
If you have Vandersteen speakers and Richard's amps you need to hear this preamp!

Seems like arc and vac are the best tube production linestages.