Best Pre for Krell Amps

I am hoping to move on a 2 channel preamp very shortly to mate with a Krell KAV amp. My requirements/objectives are the following:

HT Pass through or Unity gain for same purpose
Remote control
Tubes or SS
Avoidance of excessive brightness

Speakers will be either Wilson or Thiel and may change back and forth from time to time.
Depends upon the speaker.
I am using a PS Audio PCA-2 with my 600cx and it sounds great. It absolutely sounds much better than the Aesthetix Calypso that I tried as well as an Audio Research LS-16 that a friend wanted to try out in my system.
Of course Krell makes preamps that work well with their amps.
280P balanced in and out sounds fantastic in my system
If you have a CAST amp then the KCT is the first choice. I have tried other preamps through my 400cx but the KCT brings all into exquisite focus.
I'd say stay in the family with Krell it's always the safest bet plus the Krell stuff holds it's value better that most if you upgrade in the family