which preamp match best with Krell Evo 402 ?

I am waiting for my Krell Evo 600 to arrive anyday now! Right now I have a Krell 700cx with a tube preamp: Einstein. I also have the Krell 505 SACD.
I think you could go all Krell to utilize their cast input, supposed to be best, so that would be a KCT or Krell Evo 202 or 222 preamp. I could be wrong w/ the model number so check to make sure.
Personally I am afraid an all cast system is too clean hence the sould might be too clinical or dry. I prefer a tube preamp's sounds and characters.
The bottome line is you could match whatever preamp that is best for your ears. There is no wrong or right. Enjoy.

The Evo 202 or the new 222 is the obvious choice imho. We completed an Evo 202/402 and Dynaudio Temptation package a few months back that sounded absolutely stunning. In the top 5 packages I've ever sold, installed, and heard.

I whole-heartedly recommend the Evo's. A very natural sound without the added bass bloat common with some of the other Krell products. This is not to say "bass bloat" is a bad characteristic if that is your taste.

There are so many good pre-amps out there, but I prefer not to mix-n-match if I don't have to. This package not only has phenominal sound, it looks absolutely stunning.

I have an EVO 222 and think it's awesome coming after a ML 326s and an ARC Ref. 3. Do use an upgraded cast cable such as Tara.

I concur on the Evo222. I have one with the Evo600s and it's great, particularly in cast mode.