which preamp match best with Krell Evo 402 ?

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.

I see either 202 or 222 will be a nice match acording to suggetions. However, Audio research Ref 3 would be another strong candidate?

Forget the pre-amp, go direct in with a DCS Elgar DAC.
Audio nirvana!