Based on this review, it would be good to stay within the Krell family and use the CAST connections:
Well I have both amps in my system now. I have the following amps to try:
Pass XP20 + Pass XA100.5
Krell EVO202 + Krell EVO402.
As expected the Krell 202 plays better on the EVO402 than the Pass when using Cast. However I found that the EVO202 also played better on the Pass power amps. The EVO 202 is very open, fast and detailed. Compared to the KCT it plays thinner but more clear.
With your krell amp I would go for the EVO202. But this amp is twice as expensive as the Pass (at least in Europe) so it should be better.